Development of Cu(InGa)Se2 Thin Film Solar Cells with Cd-Free Buffer Layers

AbstractCu(InGa)Se2(CIGS) thin film absorbers were fabricated by a three-stage method using a coevaporation apparatus. As a Cd-free buffer layer, ZnSe, InxSe, GaxSey and ZnInxSey buffer layers have been deposited on the CIGS absorber continuously in the same apparatus. Atomic layer deposition (ALD) was employed as a growth technique for ZnSe. This technique offers a good thickness control as well as a good surface coverage. By irradiating with a solar simulator, all the solar cell parameters increased drastically for the first 50 minutes of the irradiation and then saturated at longer irradiation times. This phenomenon did not appear for the cells with a CdS buffer layer. The best efficiency of ZnO/ZnSe/CIGS thin film solar cells with about 10 nm thick ZnSe buffer layer was 11.6%. On the other hand, ZnO/InxSey/CIGS thin film solar cells showed very stable characteristics under the light illumination, and initial measurements show an efficiency of 13.0%.

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A review on atomic layer deposited buffer layers for Cu(In,Ga)Se2 (CIGS) thin film solar cells: Past, present, and future

Solar Energy ◽

10.1016/j.solener.2020.09.022 ◽

2020 ◽

Vol 209 ◽

pp. 515-537

Author(s):

Soumyadeep Sinha ◽

Dip K. Nandi ◽

Pravin S. Pawar ◽

Soo-Hyun Kim ◽

Jaeyeong Heo

Keyword(s):

Thin Film ◽

Solar Cells ◽

Atomic Layer ◽

Buffer Layers ◽

Thin Film Solar Cells ◽

Cigs Thin Film

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Buffer layer replacement: A method for increasing the conversion efficiency of CIGS thin film solar cells

Optik ◽

10.1016/j.ijleo.2017.02.037 ◽

2017 ◽

Vol 136 ◽

pp. 222-227 ◽

Cited By ~ 6

Author(s):

M. Moradi ◽

R. Teimouri ◽

M. Saadat ◽

M. Zahedifar

Keyword(s):

Thin Film ◽

Solar Cells ◽

Buffer Layer ◽

Conversion Efficiency ◽

Thin Film Solar Cells ◽

Cigs Thin Film

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Application of ALD-Al2O3 in CdS/CdTe Thin-Film Solar Cells

Energies ◽

10.3390/en12061123 ◽

2019 ◽

Vol 12 (6) ◽

pp. 1123 ◽

Cited By ~ 2

Author(s):

Guanggen Zeng ◽

Xia Hao ◽

Shengqiang Ren ◽

Lianghuan Feng ◽

Qionghua Wang

Keyword(s):

Thin Film ◽

Solar Cells ◽

Atomic Layer ◽

Transparent Conductive Oxide ◽

Buffer Layers ◽

Thin Film Solar Cells ◽

Window Layer ◽

Cdte Thin Film ◽

Cell Conversion ◽

Al2o3 Films

The application of thinner cadmium sulfide (CdS) window layer is a feasible approach to improve the performance of cadmium telluride (CdTe) thin film solar cells. However, the reduction of compactness and continuity of thinner CdS always deteriorates the device performance. In this work, transparent Al2O3 films with different thicknesses, deposited by using atomic layer deposition (ALD), were utilized as buffer layers between the front electrode transparent conductive oxide (TCO) and CdS layers to solve this problem, and then, thin-film solar cells with a structure of TCO/Al2O3/CdS/CdTe/BC/Ni were fabricated. The characteristics of the ALD-Al2O3 films were studied by UV–visible transmittance spectrum, Raman spectroscopy, and atomic force microscopy (AFM). The light and dark J–V performances of solar cells were also measured by specific instrumentations. The transmittance measurement conducted on the TCO/Al2O3 films verified that the transmittance of TCO/Al2O3 were comparable to that of single TCO layer, meaning that no extra absorption loss occurred when Al2O3 buffer layers were introduced into cells. Furthermore, due to the advantages of the ALD method, the ALD-Al2O3 buffer layers formed an extremely continuous and uniform coverage on the substrates to effectively fill and block the tiny leakage channels in CdS/CdTe polycrystalline films and improve the characteristics of the interface between TCO and CdS. However, as the thickness of alumina increased, the negative effects of cells were gradually exposed, especially the increase of the series resistance (Rs) and the more serious “roll-over” phenomenon. Finally, the cell conversion efficiency (η) of more than 13.0% accompanied by optimized uniformity performances was successfully achieved corresponding to the 10 nm thick ALD-Al2O3 thin film.

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Solution-Processed CdTe Thin-Film Solar Cells Using ZnSe Nanocrystal as a Buffer Layer

Applied Sciences ◽

10.3390/app8071195 ◽

2018 ◽

Vol 8 (7) ◽

pp. 1195 ◽

Cited By ~ 1

Author(s):

Yanru Chen ◽

Xianglin Mei ◽

Xiaolin Liu ◽

Bin Wu ◽

Junfeng Yang ◽

...

Keyword(s):

Thin Film ◽

Solar Cells ◽

Buffer Layer ◽

High Efficiency ◽

Low Cost ◽

Buffer Layers ◽

Thin Film Solar Cells ◽

Solution Processed ◽

Cdte Nanocrystal ◽

First Time

The CdTe nanocrystal (NC) is an outstanding, low-cost photovoltaic material for highly efficient solution-processed thin-film solar cells. Currently, most CdTe NC thin-film solar cells are based on CdSe, ZnO, or CdS buffer layers. In this study, a wide bandgap and Cd-free ZnSe NC is introduced for the first time as the buffer layer for all solution-processed CdTe/ZnSe NC hetero-junction thin-film solar cells with a configuration of ITO/ZnO/ZnSe/CdTe/MoOx/Au. The dependence of the thickness of the ZnSe NC film, the annealing temperature and the chemical treatment on the performance of NC solar cells are investigated and discussed in detail. We further develop a ligand-exchanging strategy that involves 1,2-ethanedithiol (EDT) during the fabrication of ZnSe NC film. An improved power conversion efficiency (PCE) of 3.58% is obtained, which is increased by 16.6% when compared to a device without the EDT treatment. We believe that using ZnSe NC as the buffer layer holds the potential for developing high-efficiency, low cost, and stable CdTe NC-based solar cells.

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Characteristics of TAA–ZnS Buffer Layer by Addition of Sodium Citrate for CIGS Thin Film Solar Cell

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.18764 ◽

2020 ◽

Vol 20 (11) ◽

pp. 6659-6664

Author(s):

Jeong Eun Park ◽

So Mang Park ◽

Eun Ji Bae ◽

Donggun Lim

Keyword(s):

Thin Film ◽

Thin Films ◽

Buffer Layer ◽

Deposition Rate ◽

Sodium Citrate ◽

Wide Bandgap ◽

Buffer Layers ◽

Thin Film Solar Cells ◽

Citrate Concentration ◽

Cigs Thin Film

Zinc Sulfide (ZnS) is an environmentally friendly material with a wide bandgap (Eg = 3.7 eV) comparable to that of cadmium sulfide (CdS) (2.4 eV), which is conventionally used as buffer layer in Cu(In,Ga)Se2 (CIGS) thin film solar cells. Conventional ZnS buffer layers are manufactured using thiourea, and, these layers possess a disadvantage in that their deposition rate is lower than that of CdS buffer layers. In this paper, thioacetamide (TAA) was used as a sulfur precursor instead of thiourea to increase the deposition rate. However, the ZnS thin films deposited with TAA exhibited a higher roughness than the ZnS thin films deposited with thiourea. Sodium citrate was therefore added to increase the uniformity and decrease the roughness of the former ZnS thin films. When sodium citrate was used, the thin films demonstrated a high transmittance via the controlled generation of particles. In the case of TAA–ZnS thin films doped with a sodium citrate concentration of 0.04 M, the granules on the surface disappeared and these thin films were denser than the TAA–ZnS thin films deposited with a lower sodium citrate concentration. It is considered that the rate of the ion-by-ion reaction increased due to the addition of sodium citrate, thereby resulting in a uniform thin film. Consequently, TAA–ZnS thin films with thicknesses of approximately 40 nm and high transmittances of 83% were obtained when a sodium citrate concentration of 0.04 M was used.

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Optimization of chemical bath deposited cadmium sulfide buffer layer for high-efficient CIGS thin film solar cells

Materials Letters ◽

10.1016/j.matlet.2017.05.117 ◽

2017 ◽

Vol 204 ◽

pp. 53-56 ◽

Cited By ~ 11

Author(s):

Zhangbo Lu ◽

Ranran Jin ◽

Ya Liu ◽

Longfei Guo ◽

Xinsheng Liu ◽

...

Keyword(s):

Thin Film ◽

Solar Cells ◽

Cadmium Sulfide ◽

Buffer Layer ◽

Thin Film Solar Cells ◽

Cigs Thin Film ◽

High Efficient

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Comprehensive Study of Light-Soaking Effect in ZnO/Cu(InGa)Se2 Solar Cells with Zn-Based Buffer Layers

MRS Proceedings ◽

10.1557/proc-668-h9.10 ◽

2001 ◽

Vol 668 ◽

Cited By ~ 7

Author(s):

Sutichai Chaisitsak ◽

Akira Yamada ◽

Makoto Konagai

Keyword(s):

Solar Cells ◽

Buffer Layer ◽

Atomic Layer ◽

Buffer Layers ◽

Window Layer ◽

Layer Deposition ◽

Cigs Thin Film ◽

Zinc Diffusion ◽

Zno Buffer Layer ◽

Comprehensive Study

ABSTRACTThe light-soaking effect in ZnO/ Cu(InGa)Se2 (CIGS) based solar cells has been studied. A CIGS thin film with Cu(InGa)(SeS)2 surface layer was obtained by selenization (H2Se)/sulfurization (H2S). A high resistively ZnO buffer layer deposited by the atomic layer deposition technique was used as a buffer layer. We found that the light-soaking effect mainly correlates with the properties of the CIGS surface, rather than with the properties of the ZnO buffer/window layer. This phenomenon can be eliminated by surface etching or doping CIGS surface with Zinc. Zinc diffusion using diethylzinc gas has been proposed in this work. To date, we have achieved efficiency of 13.9% (Voc: 560 mV, Jsc: 35.0 mA/cm2, FF: 0.71) without light soaking effect.

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