OSA's Digital Library

Energy Express

Energy Express

  • Editor: Christian Seassal
  • Vol. 21, Iss. S2 — Mar. 11, 2013
  • pp: A276–A284
« Show journal navigation

Multi-scale and angular analysis of ray-optical light trapping schemes in thin-film solar cells: Micro lens array, V-shaped configuration, and double parabolic trapper

Changsoon Cho and Jung-Yong Lee  »View Author Affiliations


Optics Express, Vol. 21, Issue S2, pp. A276-A284 (2013)
http://dx.doi.org/10.1364/OE.21.00A276


View Full Text Article

Acrobat PDF (1792 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

An efficient light trapping scheme is a key to enhancing the power conversion efficiency (PCE) of thin-film photovoltaic (PV) cells by compensating for the insufficient light absorption. To handle optical components from nano-scale to micro-scale seamlessly, a multi-scale optical simulation is carefully designed in this study and is used to qualitatively analyze the light trapping performances of a micro lens array (MLA), a V-shaped configuration, and the newly proposed scheme, which is termed a double parabolic trapper (DPT) according to both daily and annual movement of the sun. DPT has the potential to enhance the PCE significantly, from 5.9% to 8.9%, for PCDTBT:PC70BM-based polymer solar cells by perfectly trapping the incident light between two parabolic PV cells.

© 2013 OSA

1. Introduction

For bulk solar cells, it is known that surface texturing on the active layers at a scale tens of micrometers can increase the optical path length to 4n2 compared to the active layers thickness in which n is the refractive index of the active material [1

1. A. Goetzberger, “Optical confinement in thin Si-solar cells by diffuse back reflectors,” in Fiftheenth IEEE Photovoltaic Specialists Conference, pp. 867–870 (1981).

4

4. M. A. Green, “Lambertian light trapping in textured solar cells and light-emitting diodes: Analytical solutions,” Prog. Photovolt. Res. Appl. 10(4), 235–241 (2002). [CrossRef]

]. Because the active layers of the bulk solar cells are sufficiently thick to be incoherent, the light trapping effect follows the ray-optical regime. The usual structures of thin-film solar cells, on the other hand, can be separated into two parts: an incoherent glass substrate and a coherent multilayer region containing the active layer. Hence, both the ray-optics and the wave-optics should be taken into account in thin-film solar cells. Previously proposed light trapping schemes using wave-optical regimes mostly include interface texturing between the thin-film layers [5

5. W. L. Bai, Q. Q. Gan, F. Bartoli, J. Zhang, L. K. Cai, Y. D. Huang, and G. F. Song, “Design of plasmonic back structures for efficiency enhancement of thin-film amorphous Si solar cells,” Opt. Lett. 34(23), 3725–3727 (2009). [CrossRef] [PubMed]

14

14. J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, “Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates,” Sol. Energy Mater. Sol. Cells 85, 1–11 (2005).

] or the surface plasmon polariton (SPP) effect to concentrate the field intensity within the active layer [15

15. A. Abass, H. H. Shen, P. Bienstman, and B. Maes, “Angle insensitive enhancement of organic solar cells using metallic gratings,” J. Appl. Phys. 109(2), 023111 (2011). [CrossRef]

22

22. J. Y. Lee and P. Peumans, “The origin of enhanced optical absorption in solar cells with metal nanoparticles embedded in the active layer,” Opt. Express 18(10), 10078–10087 (2010). [CrossRef] [PubMed]

]. Compared to these wave-optical schemes, ray-optical light trapping regimes that modify the incoherent region have some advantages, as they can avoid the electrical defect which can arise in the wave-optical regime by modifying the active layer, while the absorption enhancement characteristic works for a broadband spectrum rather than a specific narrowband spectrum. Such ray-optical schemes have recently been studied [23

23. K. Tvingstedt, S. Dal Zilio, O. Inganäs, and M. Tormen, “Trapping light with micro lenses in thin film organic photovoltaic cells,” Opt. Express 16(26), 21608–21615 (2008). [CrossRef] [PubMed]

27

27. M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, “Functional microprism substrate for organic solar cells,” Thin Solid Films 511, 628–633 (2006). [CrossRef]

], but theoretical analyses of these schemes are relatively rare.

To devise optimal ray-optical light trapping schemes, their performances should be precisely appraised by a proper simulation analysis and should be fairly compared to those of other schemes. However, thin-film PVs have both coherent regions consisting of a nanometer-scale multilayer structure and incoherent regions consisting of micrometer-scale optical components such as a substrate. For this reason, it is not a simple matter to evaluate the spectral response of these devices without proper analytical schemes. Therefore, a multi-scale approach is necessary for an accurate estimation of the light trapping performances of different configurations in thin-film PVs. Moreover, because most light trapping schemes are influenced by the incident angle and given that a solar-tracking system is generally not feasible for use in thin-film PVs at a low cost, the optical property only at the normal incident angle does not sufficiently represent the performance of the PV system. A simulation study should take the entire range of incident angle variation as caused by the annual sun movement into consideration, though this has been often neglected.

Here, we implement an optical simulation to consider both ray-optical and wave-optical characteristics and use it for a precise evaluation of the angular performances of previously proposed light trapping schemes, a micro lens array (MLA) and V-shaped configurations. Moreover, we propose an ideal configuration, which we term double parabolic trapper (DPT) using the geometrical characteristics of the parabolas to achieve the theoretically perfect absorption of the incident light.

2. Multi-scale properties of thin-film PVs

The multi-scalability of thin-film PVs necessitates careful attention when conducting optical analyses, contrary to bulk PVs. In bulk cells with micro-scale active layers, incoherent ray-optics is sufficient to evaluate the optical performance. As a general rule, an oblique propagation angle is always considered to be advantageous to increase the optical path length in the bulk active layers. However, in thin-film PVs, both nano-scale and micro-scale structures coexist in the devices. As many nano-scale layers with different materials are stacked on the micro-scale substrate, geometrical path length enhancement by means ofoblique propagation with an incoherent optical calculation cannot represent the thin-film device characteristics [28

28. P. Peumans, A. Yakimov, and S. R. Forrest, “Small molecular weight organic thin-film photodetectors and solar cells,” J. Appl. Phys. 93(7), 3693–3723 (2003). [CrossRef]

, 29

29. L. A. A. Pettersson, L. S. Roman, and O. Inganas, “Modeling photocurrent action spectra of photovoltaic devices based on organic thin films,” J. Appl. Phys. 86(1), 487–496 (1999). [CrossRef]

]. Figure 1(a)
Fig. 1 (a) Absorption characteristics of the active layer according to the propagation angle variation (represented in the inset) for a thin-film PV using PCDTBT:PC70BM as an active material for TE (open) and TM (closed) polarized light with a wavelength of 500nm. The purple and green lines indicate the incoherent and coherent calculation, respectively. (b) n (real part) and k (imaginary part) values of the refractive indices used in the optical simulations. (c) Description of the annual (θa) and daily (θd) incident angle variation, where a 1D array structure is aligned along the east–west line.
shows the absorption characteristics of the active layer along the propagation angle (θprop) calculated with and without considering the coherency of the incident light at a specific wavelength of 500 nm for a PV structure of glass / ITO (75 nm) / ZnO (27 nm) / PCDTBT:PC70BM (80 nm) / MoO3 (10 nm) / Ag, where ITO, PCDTBT and PC70BM refer to indium tin oxide, poly[9’-hepta-decanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3′-benzothiadiazole) and [6,6]-phenyl C 71 -butyric acid methyl ester, respectively [30

30. S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009). [CrossRef]

32

32. X. H. Li, W. C. H. Choy, L. J. Huo, F. X. Xie, W. E. I. Sha, B. F. Ding, X. Guo, Y. F. Li, J. H. Hou, J. B. You, and Y. Yang, “Dual plasmonic nanostructures for high performance inverted organic solar cells,” Adv. Mater. (Deerfield Beach Fla.) 24(22), 3046–3052 (2012). [CrossRef] [PubMed]

]. The refractive indices for the simulations obtained by ellipsometry are shown in Fig. 1(b); they were assumed to be isotropic for simplification. Transfer-matrix formalism (TMF) for both TE and TM modes was used to calculate the absorption of the multilayer structure in the coherent model [28

28. P. Peumans, A. Yakimov, and S. R. Forrest, “Small molecular weight organic thin-film photodetectors and solar cells,” J. Appl. Phys. 93(7), 3693–3723 (2003). [CrossRef]

, 29

29. L. A. A. Pettersson, L. S. Roman, and O. Inganas, “Modeling photocurrent action spectra of photovoltaic devices based on organic thin films,” J. Appl. Phys. 86(1), 487–496 (1999). [CrossRef]

]. In the incoherent model, Fresnel transmission and reflection were considered at each interface, as in the TMF calculation, but the coherencies between propagating waves were removed by considering the waves to be rays in the nano-scale multilayers. While the overall tendency of the absorption of both models agrees qualitatively, the incoherent model seriously underestimates the actual absorption as calculated by the coherent model, as revealed in Fig. 1(a). The discrepancy between the two models came from an interference effect that can exist only in the coherent region. The interference effect can induce extra absorption by concentrating the electromagnetic field in the active layers. This is the main difference between thin-film PVs and bulk PVs, in which the absorption increases only geometrically. Therefore, a proper optical simulation that considers such properties should be conducted to evaluate the performances of the ray-optical light trapping configurations on thin-film PVs. It should be noted that the sharp decrease of the active absorption in both models at a large propagation angle is mainly caused by the increased Fresnel reflections at the interface between the glass substrate and the top transparent electrode.

For a complete evaluation of the given optical configurations, the entire annual movement of the sun must be taken into account because the performances of ray-optical light trapping schemes tend to be dependent on the incident angle of light. While the annual sun height variation is confined to within ± 23.5°, the daily sun movement covers the full 180° from east to west. The performance variation according to the daily sun movement may be minimized by aligning the cross-sectional plane of a 1D array type configuration perpendicular to the axis along east to west, as depicted in Fig. 1(c); the incident angle projected onto the cross-section is then constant for a complete day [23

23. K. Tvingstedt, S. Dal Zilio, O. Inganäs, and M. Tormen, “Trapping light with micro lenses in thin film organic photovoltaic cells,” Opt. Express 16(26), 21608–21615 (2008). [CrossRef] [PubMed]

, 33

33. T. K. Mallick and P. C. Eames, “Design and fabrication of low concentrating second generation PRIDE concentrator,” Sol. Energy Mater. Sol. Cells 91(7), 597–608 (2007). [CrossRef]

35

35. K. Yoshioka, A. Suzuki, and T. Saitoh, “Performance evaluation of two-dimensional compound elliptic lens concentrators using a yearly distributed insolation model,” Sol. Energy Mater. Sol. Cells 57(1), 9–19 (1999). [CrossRef]

]. In this paper, we define the annual incident angle (θa) as the incident angle projected onto the cross-section of a 1D array type configuration, which varies within ± 23.5° annually when the system is tilted at the altitude of the location. The daily incident angle (θd) is defined as the angle between the incident ray and the cross-section, which varies within ± 90° every day. Note that θa becomes 0° in spring and fall, and ± 23.5° in summer or winter, while θd of ± 90° corresponds to the time of sunrise or sunset.

3. Analysis on light trapping schemes

3.1 Micro lens array (MLA)

Trapping light using an MLA is an easy way to reduce the escape probability of internal rays and increase the probability that the rays will be absorbed by the photovoltaic cells. Tvingstedt et al. presented such a scheme using an MLA for light trapping with a highly restricted acceptance angle [23

23. K. Tvingstedt, S. Dal Zilio, O. Inganäs, and M. Tormen, “Trapping light with micro lenses in thin film organic photovoltaic cells,” Opt. Express 16(26), 21608–21615 (2008). [CrossRef] [PubMed]

]. The configuration of a 1D MLA structure and corresponding simulation results are shown in Fig. 2(a)
Fig. 2 (a) Light trapping system using MLA, (b) normalized Jsc variations with the variations of θa and θd for MLA-PV with different widths over the period (Went). Ray-traced cross-section images for θa = 0° are shown in the inset when θd = 0°, 30° and 60°. To obtain a clear picture, the bottom cell and blocking mirrors were assumed to absorb the light for ray-tracing perfectly. (c) The contours of points (θa, θd), where the normalized Jsc becomes 1 for MLA-PVs when Went = 0.10 and 0.15, respectively.
and 2(b), respectively. The incident rays are focused onto small entrances by the lens arrays, and blocking mirrors are implemented to prevent the internal rays from escaping the system. Assuming that the internal rays are sufficiently randomized, the escape probability of the internal rays of this system is equal to the ratio of the entrance width to the period. For the simulation, the period of the structure was 400 μmand lens was designed by a cylindrical approximation with a radius of 328.9 μm; a cylindrical approximation was made considering the manufacturing process using isotropic etching in the literature [23

23. K. Tvingstedt, S. Dal Zilio, O. Inganäs, and M. Tormen, “Trapping light with micro lenses in thin film organic photovoltaic cells,” Opt. Express 16(26), 21608–21615 (2008). [CrossRef] [PubMed]

, 36

36. S. Dal Zilio, K. Tvingstedt, O. Inganas, and M. Tormen, “Fabrication of a light trapping system for organic solar cells,” Microelectron. Eng. 86(4-6), 1150–1154 (2009). [CrossRef]

]. The theoretical focal length was 1000 μm for the structure with PMMA (n = 1.49). However, within the cylindrical approximation, the real curved surface of the vertex lens has larger curvature compared to the ideally thin lens shape and the practical focal length is shorter; therefore, we reduced the lens thickness to 940 μm.

Figure 2(b) shows the MLA-PV systems when Went = 0.10 and 0.15 at noon (i.e., θd = 0°) resulting in the maximum Jsc enhancements of approx. 33.7% (PCE = 7.9%) and 29.3% (PCE = 7.6%), respectively, where Went indicates the relative entrance width over the period. However, no enhancement can be guaranteed when the annual acceptance angle is larger than 1.3° (Went = 0.10) and 2.2° (Went = 0.15); the enhancement is in a trade-off relationship with the value of Went, which eventually determines the acceptance angle. The Went value of the MLA-PV systems restricts the acceptance angle along not only θa but also θd. For example, when θd = 30° and 60°, the focal point became shorter; hence, the rays do not perfectly fall into the entrance even when θa = 0°, as shown in the inset of Fig. 2(b). This occurs because the refraction on the lens surface cannot be dealt with by Snell’s law independently for θa and θd. The points (θa, θd) of the normalized Jsc equal to 1 are plotted in Fig. 2(c). MLA-PV with a larger entrance (Went = 0.15) has a slightly larger acceptance angle region. Narrow acceptance angles of the MLA-PV systems in both directions imply that we need a 2D solar tracking system to make full use of the MLA, potentially increasing the cost of the PV system.

3.2 V-shaped structure

For bulk solar cells with a restricted acceptance angle of 2θ < 180°, it is known that the limit of the optical path length enhancement can be increased to 4n2/sin2θ [2

2. E. Yablonovitch, “Statistical ray optics,” J. Opt. Soc. Am. A 72(7), 899–907 (1982). [CrossRef]

, 21

21. Z. F. Yu, A. Raman, and S. H. Fan, “Fundamental limit of light trapping in grating structures,” Opt. Express 18(S3Suppl 3), A366–A380 (2010). [CrossRef] [PubMed]

]. The fundamental trade-off relationship between the light trapping effect and the acceptance angle can explain the narrow acceptance angle of MLA-PV with a large Jsc enhancement. However, the trade-off relationship can be overcome using a larger PV area than the module area, such as in a V-shaped structure, as presented by Tvingstedt et al. and Rim et al., independently [25

25. K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, “Folded reflective tandem polymer solar cell doubles efficiency,” Appl. Phys. Lett. 91(12), 123514 (2007). [CrossRef]

, 26

26. S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, “An effective light trapping configuration for thin-film solar cells,” Appl. Phys. Lett. 91(24), 243501 (2007). [CrossRef]

]. The V-shaped structure and its simulation results with various vertex angles (θv) are shown in Figs. 3(a)
Fig. 3 (a) V-shaped light trapping configuration, (b) normalized Jsc variation with the variation of θa (where θd = 0°) for V-shaped PVs with the different vertex angles (θv).
and 3(b), respectively. The Jsc enhancement increases with a decrease in θv and the maximum enhancement with a θv value of 40° is 40.7% (PCE = 8.3%), while it is still 35.7% with a θa value of 23.5°, which corresponds to the maximum incident angle for a whole year where the system is aligned at an east–west orientation and is tilted at the altitudeof the location, as discussed above. Unlike the MLA system, the V-shaped configuration manipulates the incident light through reflection rather than refraction, implying that the ray trajectories that are projected on the cross-section of the V-shaped array are independent of θd and that the light trapping effect is mainly dependent on the value of θa. For an θa value larger than (180° − θv) / 2, the V-shaped array does not trap the rays because all of the incident rays bounce on the PV only once and escape the system [26

26. S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, “An effective light trapping configuration for thin-film solar cells,” Appl. Phys. Lett. 91(24), 243501 (2007). [CrossRef]

]. Hence, the normalized Jsc reaches its smallest point at θa values of 70°, 60° and 50° when θv is equal to 40°, 60° and 80°, respectively. It starts to increase again as θa increases given the reference Jsc of a planar PV with such an angle rapidly decreasing due to the increased optical loss caused by Fresnel reflection on the substrate.

As shown in Fig. 3(b), both a strong light trapping effect and a large acceptance angle are achieved simultaneously by the V-shaped scheme. Because the PV area over the module area increases as θv decreases (2.92-fold for θv = 40°), the density of the light intensity is quite low over the PV area and the actual light trapping effect does not overcome the trade-off relationship with the acceptance angle in terms of the actual PV area. However, with the simple trick of folding planar PVs into a small module area, a greatly increased PCE is achieved over a large incident angle range. The cost of the increased material usage may not be a significant problem when using an inexpensive active material. Moreover, a tandem structure can be easily implemented using two different materials on each side, as proposed by Tvingstedt et al. [25

25. K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, “Folded reflective tandem polymer solar cell doubles efficiency,” Appl. Phys. Lett. 91(12), 123514 (2007). [CrossRef]

]. This implies that we do not merely have to stack PVs with different band-gaps and that we can obtain both a multi-junction effect and an enhancement of the light trapping effect simultaneously. However, there remain some practical problems to be resolved, such as the complicated fabrication process, the increased volume, and the weights of the modules, with an unequal absorption distribution on each cell and an Voc drop caused by the decreased absorption density [26

26. S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, “An effective light trapping configuration for thin-film solar cells,” Appl. Phys. Lett. 91(24), 243501 (2007). [CrossRef]

].

3.3 Double parabolic trapper (DPT)

Lastly, in order to achieve perfect light absorption, we propose an ideal configuration, called DPT, as depicted in Fig. 4(a)
Fig. 4 (a) Geometrical characteristic of a parabola concentrating all of the incident rays parallel to the axis into a focus or reflecting them in a reverse manner (above), and DPT structure for perfect light trapping (below), (b) normalized Jsc variation with the variation of θa (θd = 0°) for DPT-PV. Ray-traced images are also shown when θa = 0° and ± 23.5°, where only rays having power greater than 10% of an initial power appear.
. It is well known that the parabola concentrates all of the normal incident rays to a focal point and that all of the rays passing the focal point in turn propagate parallel to the central axis upon the reflection on the parabola [see Fig. 4(a)]. We designed two different sizes of parabolas which face each other, and which share the same focal point. Then, a ray once passing the point keeps circulating between the parabolas indefinitely.

If the PVs are implemented on the surface of the two parabolas and a front mirror, as shown in the red regions in Fig. 4(a), and if the multilayer structures do not disturb the direction of the reflected rays, perfect light trapping can be achieved. An enhancement of 50.9% was achieved when θa = 0° in the simulation, and the total device absorption becomes100% in such a case. This implies that the PCE of the PV cell can be increased from 5.9% to 8.9% by light trapping only without any modification of the multilayer structure. Note that this does not imply that the external quantum efficiency (EQE) reaches the IQE, as the total device absorption also includes the parasitic absorption of the non-active layers, such as the metal electrode, which would not generate any photocurrent. The space between the two parabolas is assumed to be a glass mold in the simulations; it may be a practical consideration to evaporate PVs on the mold.

Interestingly, the DPT-PV scheme also shows good performance even for large variations of θa, although the tracing principle discussed above does not simply apply. Since the trapping scheme in DPT is also based on reflection, as in the V-shaped configuration, rather than refraction, the performance is almost independent of θd. Therefore, a Jsc enhancement of more than 30% is guaranteed for an entire year (−23.5° < θa < 23.5°) in this system. The ray-traced results for θa = 0° and ± 23.5° are depicted in the insets of Fig. 4(b). Although the detailed working principle cannot easily be elucidated for each value of θa, the rays reflected by the tilted front PV bounce many times on other PV areas in various ways. The outstanding enhancement over a wide range of incident angles is due to the larger PV area compared to the module area (4.79-fold), as in the V-shaped system. The possibility of a tandem application implementing two different PVs on each parabolic side is also an advantage of DPT-PV, similar to the V-shaped configuration scheme discussed above. As in the V-shaped PV, unequal and low light intensity over the PV area of the DPT configurations may cause degradation of the electrical properties such as IQE, Voc, and FF.

4. Summary

In summary, we analyzed the light trapping effect of thin-film PVs by considering both ray-optical and wave-optical characteristics of the system. The trapping scheme using an MLA focuses on suppressing the escape of the internal rays and having them return to the photovoltaic layer. However, owing to a trade-off relationship, the performances of such schemes are highly restricted by the narrow acceptance angle. On the other hand, the V-shaped configuration utilizes a larger active area compared to the module area and hence further improves the light absorption without sacrificing the acceptance angle. Finally, we propose a configuration termed DPT as a perfect light trapping scheme. DPT-PV shows a Jsc enhancement of up to 50.9% when using the geometrical characteristics of a parabola at the normal incident angle while also showing a good angular response. In addition to the optical performance, the V-shaped and DPT schemes may also be used in tandem, but practical problems such as the complicated fabrication process should be overcome before commercialization can be realized. A comparison of the MLA, V-shaped and DPT schemes is summarized in Table 1

Table 1. Summary of the light trapping characteristics for the MLA, V-shaped and DPT configurations

table-icon
View This Table
.

Acknowledgments

We sincerely appreciate the financial support from the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (MEST) (2012-0003991). We also gratefully acknowledge support from the Center for Inorganic Photovoltaic Materials (2012–0001172) through a grant funded by the MEST, grant No. EEWS-2012-N01120012 from the EEWS Research Project of the office of the KAIST EEWS Initiative, KAIST Institute for the NanoCentury, and Samsung Display Co. C. Cho acknowledges financial support from the Korea Foundation for Advanced Studies (KFAS).

References and links

1.

A. Goetzberger, “Optical confinement in thin Si-solar cells by diffuse back reflectors,” in Fiftheenth IEEE Photovoltaic Specialists Conference, pp. 867–870 (1981).

2.

E. Yablonovitch, “Statistical ray optics,” J. Opt. Soc. Am. A 72(7), 899–907 (1982). [CrossRef]

3.

P. Campbell and M. A. Green, “Light trapping properties of pyramidally textured surfaces,” J. Appl. Phys. 62(1), 243–249 (1987). [CrossRef]

4.

M. A. Green, “Lambertian light trapping in textured solar cells and light-emitting diodes: Analytical solutions,” Prog. Photovolt. Res. Appl. 10(4), 235–241 (2002). [CrossRef]

5.

W. L. Bai, Q. Q. Gan, F. Bartoli, J. Zhang, L. K. Cai, Y. D. Huang, and G. F. Song, “Design of plasmonic back structures for efficiency enhancement of thin-film amorphous Si solar cells,” Opt. Lett. 34(23), 3725–3727 (2009). [CrossRef] [PubMed]

6.

R. Dewan, M. Marinkovic, R. Noriega, S. Phadke, A. Salleo, and D. Knipp, “Light trapping in thin-film silicon solar cells with submicron surface texture,” Opt. Express 17(25), 23058–23065 (2009). [CrossRef] [PubMed]

7.

O. Kluth, B. Rech, L. Houben, S. Wieder, G. Schope, C. Beneking, H. Wagner, A. Loffl, and H. W. Schock, “Texture etched ZnO: Al coated glass substrates for silicon based thin film solar cells,” Thin Solid Films 351(1-2), 247–253 (1999). [CrossRef]

8.

J. Krc, M. Zeman, O. Kluth, E. Smole, and M. Topic, “Effect of surface roughness of ZnO: Al films on light scattering in hydrogenated amorphous silicon solar cells,” Thin Solid Films 426(1-2), 296–304 (2003). [CrossRef]

9.

J. M. Lee, S. J. Yun, J. K. Kim, and J. W. Lim, “Texturing of Ga-Doped ZnO Transparent Electrode for a-Si: H Thin Film Solar Cells,” Electrochem. Solid State 14(11), B124–B126 (2011). [CrossRef]

10.

J. Muller, G. Schope, O. Kluth, B. Rech, V. Sittinger, B. Szyszka, R. Geyer, P. Lechner, H. Schade, M. Ruske, G. Dittmar, and H. P. Bochem, “State-of-the-art mid-frequency sputtered ZnO films for thin film silicon solar cells and modules,” Thin Solid Films 442(1-2), 158–162 (2003). [CrossRef]

11.

J. Muller, B. Rech, J. Springer, and M. Vanecek, “TCO and light trapping in silicon thin film solar cells,” Sol. Energy 77(6), 917–930 (2004). [CrossRef]

12.

B. Rech and H. Wagner, “Potential of amorphous silicon for solar cells,” Appl. Phys. A-Mater. 69, 155–167 (1999).

13.

F. Ruske, C. Jacobs, V. Sittinger, B. Szyszka, and W. Werner, “Large area ZnO: Al films with tailored-light scattering properties for photovoltaic applications,” Thin Solid Films 515(24), 8695–8698 (2007). [CrossRef]

14.

J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, “Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates,” Sol. Energy Mater. Sol. Cells 85, 1–11 (2005).

15.

A. Abass, H. H. Shen, P. Bienstman, and B. Maes, “Angle insensitive enhancement of organic solar cells using metallic gratings,” J. Appl. Phys. 109(2), 023111 (2011). [CrossRef]

16.

C. J. Min, J. Li, G. Veronis, J. Y. Lee, S. H. Fan, and P. Peumans, “Enhancement of optical absorption in thin-film organic solar cells through the excitation of plasmonic modes in metallic gratings,” Appl. Phys. Lett. 96(13), 133302 (2010). [CrossRef]

17.

S. I. Na, S. S. Kim, J. Jo, S. H. Oh, J. Kim, and D. Y. Kim, “Efficient Polymer Solar Cells with Surface Relief Gratings Fabricated by Simple Soft Lithography,” Adv. Funct. Mater. 18(24), 3956–3963 (2008). [CrossRef]

18.

S. I. Na, S.-S. Kim, S. S. Kwon, J. Jang, K. Juhwan, T. Lee, and K. Dong-Yu, “Surface relief gratings on poly(3-hexylthiophene) and fullerene blends for efficient organic solar cells,” Appl. Phys. Lett. 91(17), 173509 (2007). [CrossRef]

19.

H. H. Shen and B. Maes, “Combined plasmonic gratings in organic solar cells,” Opt. Express 19(S6Suppl 6), A1202–A1210 (2011). [CrossRef] [PubMed]

20.

K. Tvingstedt, N. K. Persson, O. Inganas, A. Rahachou, and I. V. Zozoulenko, “Surface plasmon increase absorption in polymer photovoltaic cells,” Appl. Phys. Lett. 91(11), 113514 (2007). [CrossRef]

21.

Z. F. Yu, A. Raman, and S. H. Fan, “Fundamental limit of light trapping in grating structures,” Opt. Express 18(S3Suppl 3), A366–A380 (2010). [CrossRef] [PubMed]

22.

J. Y. Lee and P. Peumans, “The origin of enhanced optical absorption in solar cells with metal nanoparticles embedded in the active layer,” Opt. Express 18(10), 10078–10087 (2010). [CrossRef] [PubMed]

23.

K. Tvingstedt, S. Dal Zilio, O. Inganäs, and M. Tormen, “Trapping light with micro lenses in thin film organic photovoltaic cells,” Opt. Express 16(26), 21608–21615 (2008). [CrossRef] [PubMed]

24.

P. Peumans, V. Bulovic, and S. R. Forrest, “Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes,” Appl. Phys. Lett. 76(19), 2650–2652 (2000). [CrossRef]

25.

K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, “Folded reflective tandem polymer solar cell doubles efficiency,” Appl. Phys. Lett. 91(12), 123514 (2007). [CrossRef]

26.

S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, “An effective light trapping configuration for thin-film solar cells,” Appl. Phys. Lett. 91(24), 243501 (2007). [CrossRef]

27.

M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, “Functional microprism substrate for organic solar cells,” Thin Solid Films 511, 628–633 (2006). [CrossRef]

28.

P. Peumans, A. Yakimov, and S. R. Forrest, “Small molecular weight organic thin-film photodetectors and solar cells,” J. Appl. Phys. 93(7), 3693–3723 (2003). [CrossRef]

29.

L. A. A. Pettersson, L. S. Roman, and O. Inganas, “Modeling photocurrent action spectra of photovoltaic devices based on organic thin films,” J. Appl. Phys. 86(1), 487–496 (1999). [CrossRef]

30.

S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics 3(5), 297–302 (2009). [CrossRef]

31.

J. Jin, J. Lee, S. Jeong, S. Yang, J.-H. Ko, H.-G. Im, S.W. Baek, J.Y. Lee, and B.S. Bae, “High-performance hybrid plastic films: A robust electrode platform for thin-film optoelectronics,” Energy Environ. Sci., DOI: [CrossRef]

32.

X. H. Li, W. C. H. Choy, L. J. Huo, F. X. Xie, W. E. I. Sha, B. F. Ding, X. Guo, Y. F. Li, J. H. Hou, J. B. You, and Y. Yang, “Dual plasmonic nanostructures for high performance inverted organic solar cells,” Adv. Mater. (Deerfield Beach Fla.) 24(22), 3046–3052 (2012). [CrossRef] [PubMed]

33.

T. K. Mallick and P. C. Eames, “Design and fabrication of low concentrating second generation PRIDE concentrator,” Sol. Energy Mater. Sol. Cells 91(7), 597–608 (2007). [CrossRef]

34.

K. Yoshioka, K. Endoh, M. Kobayashi, A. Suzuki, and T. Saitoh, “Design and properties of a refractive static concentrator module,” Sol. Energy Mater. Sol. Cells 34(1-4), 125–131 (1994). [CrossRef]

35.

K. Yoshioka, A. Suzuki, and T. Saitoh, “Performance evaluation of two-dimensional compound elliptic lens concentrators using a yearly distributed insolation model,” Sol. Energy Mater. Sol. Cells 57(1), 9–19 (1999). [CrossRef]

36.

S. Dal Zilio, K. Tvingstedt, O. Inganas, and M. Tormen, “Fabrication of a light trapping system for organic solar cells,” Microelectron. Eng. 86(4-6), 1150–1154 (2009). [CrossRef]

OCIS Codes
(040.5350) Detectors : Photovoltaic
(160.4890) Materials : Organic materials
(350.6050) Other areas of optics : Solar energy
(310.6845) Thin films : Thin film devices and applications

ToC Category:
Photovoltaics

History
Original Manuscript: December 21, 2012
Revised Manuscript: February 7, 2013
Manuscript Accepted: February 9, 2013
Published: February 21, 2013

Citation
Changsoon Cho and Jung-Yong Lee, "Multi-scale and angular analysis of ray-optical light trapping schemes in thin-film solar cells: Micro lens array, V-shaped configuration, and double parabolic trapper," Opt. Express 21, A276-A284 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-S2-A276


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. A. Goetzberger, “Optical confinement in thin Si-solar cells by diffuse back reflectors,” in Fiftheenth IEEE Photovoltaic Specialists Conference, pp. 867–870 (1981).
  2. E. Yablonovitch, “Statistical ray optics,” J. Opt. Soc. Am. A72(7), 899–907 (1982). [CrossRef]
  3. P. Campbell and M. A. Green, “Light trapping properties of pyramidally textured surfaces,” J. Appl. Phys.62(1), 243–249 (1987). [CrossRef]
  4. M. A. Green, “Lambertian light trapping in textured solar cells and light-emitting diodes: Analytical solutions,” Prog. Photovolt. Res. Appl.10(4), 235–241 (2002). [CrossRef]
  5. W. L. Bai, Q. Q. Gan, F. Bartoli, J. Zhang, L. K. Cai, Y. D. Huang, and G. F. Song, “Design of plasmonic back structures for efficiency enhancement of thin-film amorphous Si solar cells,” Opt. Lett.34(23), 3725–3727 (2009). [CrossRef] [PubMed]
  6. R. Dewan, M. Marinkovic, R. Noriega, S. Phadke, A. Salleo, and D. Knipp, “Light trapping in thin-film silicon solar cells with submicron surface texture,” Opt. Express17(25), 23058–23065 (2009). [CrossRef] [PubMed]
  7. O. Kluth, B. Rech, L. Houben, S. Wieder, G. Schope, C. Beneking, H. Wagner, A. Loffl, and H. W. Schock, “Texture etched ZnO: Al coated glass substrates for silicon based thin film solar cells,” Thin Solid Films351(1-2), 247–253 (1999). [CrossRef]
  8. J. Krc, M. Zeman, O. Kluth, E. Smole, and M. Topic, “Effect of surface roughness of ZnO: Al films on light scattering in hydrogenated amorphous silicon solar cells,” Thin Solid Films426(1-2), 296–304 (2003). [CrossRef]
  9. J. M. Lee, S. J. Yun, J. K. Kim, and J. W. Lim, “Texturing of Ga-Doped ZnO Transparent Electrode for a-Si: H Thin Film Solar Cells,” Electrochem. Solid State14(11), B124–B126 (2011). [CrossRef]
  10. J. Muller, G. Schope, O. Kluth, B. Rech, V. Sittinger, B. Szyszka, R. Geyer, P. Lechner, H. Schade, M. Ruske, G. Dittmar, and H. P. Bochem, “State-of-the-art mid-frequency sputtered ZnO films for thin film silicon solar cells and modules,” Thin Solid Films442(1-2), 158–162 (2003). [CrossRef]
  11. J. Muller, B. Rech, J. Springer, and M. Vanecek, “TCO and light trapping in silicon thin film solar cells,” Sol. Energy77(6), 917–930 (2004). [CrossRef]
  12. B. Rech and H. Wagner, “Potential of amorphous silicon for solar cells,” Appl. Phys. A-Mater.69, 155–167 (1999).
  13. F. Ruske, C. Jacobs, V. Sittinger, B. Szyszka, and W. Werner, “Large area ZnO: Al films with tailored-light scattering properties for photovoltaic applications,” Thin Solid Films515(24), 8695–8698 (2007). [CrossRef]
  14. J. Springer, B. Rech, W. Reetz, J. Muller, and M. Vanecek, “Light trapping and optical losses in microcrystalline silicon pin solar cells deposited on surface-textured glass/ZnO substrates,” Sol. Energy Mater. Sol. Cells85, 1–11 (2005).
  15. A. Abass, H. H. Shen, P. Bienstman, and B. Maes, “Angle insensitive enhancement of organic solar cells using metallic gratings,” J. Appl. Phys.109(2), 023111 (2011). [CrossRef]
  16. C. J. Min, J. Li, G. Veronis, J. Y. Lee, S. H. Fan, and P. Peumans, “Enhancement of optical absorption in thin-film organic solar cells through the excitation of plasmonic modes in metallic gratings,” Appl. Phys. Lett.96(13), 133302 (2010). [CrossRef]
  17. S. I. Na, S. S. Kim, J. Jo, S. H. Oh, J. Kim, and D. Y. Kim, “Efficient Polymer Solar Cells with Surface Relief Gratings Fabricated by Simple Soft Lithography,” Adv. Funct. Mater.18(24), 3956–3963 (2008). [CrossRef]
  18. S. I. Na, S.-S. Kim, S. S. Kwon, J. Jang, K. Juhwan, T. Lee, and K. Dong-Yu, “Surface relief gratings on poly(3-hexylthiophene) and fullerene blends for efficient organic solar cells,” Appl. Phys. Lett.91(17), 173509 (2007). [CrossRef]
  19. H. H. Shen and B. Maes, “Combined plasmonic gratings in organic solar cells,” Opt. Express19(S6Suppl 6), A1202–A1210 (2011). [CrossRef] [PubMed]
  20. K. Tvingstedt, N. K. Persson, O. Inganas, A. Rahachou, and I. V. Zozoulenko, “Surface plasmon increase absorption in polymer photovoltaic cells,” Appl. Phys. Lett.91(11), 113514 (2007). [CrossRef]
  21. Z. F. Yu, A. Raman, and S. H. Fan, “Fundamental limit of light trapping in grating structures,” Opt. Express18(S3Suppl 3), A366–A380 (2010). [CrossRef] [PubMed]
  22. J. Y. Lee and P. Peumans, “The origin of enhanced optical absorption in solar cells with metal nanoparticles embedded in the active layer,” Opt. Express18(10), 10078–10087 (2010). [CrossRef] [PubMed]
  23. K. Tvingstedt, S. Dal Zilio, O. Inganäs, and M. Tormen, “Trapping light with micro lenses in thin film organic photovoltaic cells,” Opt. Express16(26), 21608–21615 (2008). [CrossRef] [PubMed]
  24. P. Peumans, V. Bulovic, and S. R. Forrest, “Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes,” Appl. Phys. Lett.76(19), 2650–2652 (2000). [CrossRef]
  25. K. Tvingstedt, V. Andersson, F. Zhang, and O. Inganas, “Folded reflective tandem polymer solar cell doubles efficiency,” Appl. Phys. Lett.91(12), 123514 (2007). [CrossRef]
  26. S. B. Rim, S. Zhao, S. R. Scully, M. D. McGehee, and P. Peumans, “An effective light trapping configuration for thin-film solar cells,” Appl. Phys. Lett.91(24), 243501 (2007). [CrossRef]
  27. M. Niggemann, M. Glatthaar, P. Lewer, C. Muller, J. Wagner, and A. Gombert, “Functional microprism substrate for organic solar cells,” Thin Solid Films511, 628–633 (2006). [CrossRef]
  28. P. Peumans, A. Yakimov, and S. R. Forrest, “Small molecular weight organic thin-film photodetectors and solar cells,” J. Appl. Phys.93(7), 3693–3723 (2003). [CrossRef]
  29. L. A. A. Pettersson, L. S. Roman, and O. Inganas, “Modeling photocurrent action spectra of photovoltaic devices based on organic thin films,” J. Appl. Phys.86(1), 487–496 (1999). [CrossRef]
  30. S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J. S. Moon, D. Moses, M. Leclerc, K. Lee, and A. J. Heeger, “Bulk heterojunction solar cells with internal quantum efficiency approaching 100%,” Nat. Photonics3(5), 297–302 (2009). [CrossRef]
  31. J. Jin, J. Lee, S. Jeong, S. Yang, J.-H. Ko, H.-G. Im, S.W. Baek, J.Y. Lee, and B.S. Bae, “High-performance hybrid plastic films: A robust electrode platform for thin-film optoelectronics,” Energy Environ. Sci., DOI: [CrossRef]
  32. X. H. Li, W. C. H. Choy, L. J. Huo, F. X. Xie, W. E. I. Sha, B. F. Ding, X. Guo, Y. F. Li, J. H. Hou, J. B. You, and Y. Yang, “Dual plasmonic nanostructures for high performance inverted organic solar cells,” Adv. Mater. (Deerfield Beach Fla.)24(22), 3046–3052 (2012). [CrossRef] [PubMed]
  33. T. K. Mallick and P. C. Eames, “Design and fabrication of low concentrating second generation PRIDE concentrator,” Sol. Energy Mater. Sol. Cells91(7), 597–608 (2007). [CrossRef]
  34. K. Yoshioka, K. Endoh, M. Kobayashi, A. Suzuki, and T. Saitoh, “Design and properties of a refractive static concentrator module,” Sol. Energy Mater. Sol. Cells34(1-4), 125–131 (1994). [CrossRef]
  35. K. Yoshioka, A. Suzuki, and T. Saitoh, “Performance evaluation of two-dimensional compound elliptic lens concentrators using a yearly distributed insolation model,” Sol. Energy Mater. Sol. Cells57(1), 9–19 (1999). [CrossRef]
  36. S. Dal Zilio, K. Tvingstedt, O. Inganas, and M. Tormen, “Fabrication of a light trapping system for organic solar cells,” Microelectron. Eng.86(4-6), 1150–1154 (2009). [CrossRef]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

Figures

Fig. 1 Fig. 2 Fig. 3
 
Fig. 4
 

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited