Nanocomposite (CuS) (ZnS)1 thin film back contact for CdTe solar cells: Toward a bifacial device
| Autor: | Zhaoning Song, Randy J. Ellingson, Adam B. Phillips, Michael J. Heben, Nikolas J. Podraza, Indra Subedi, Ebin Bastola, Kamala Khanal Subedi, Khagendra P. Bhandari |
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| Rok vydání: | 2018 |
| Předmět: |
010302 applied physics
Materials science Nanocomposite Opacity Renewable Energy Sustainability and the Environment business.industry 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Cadmium telluride photovoltaics Surfaces Coatings and Films Electronic Optical and Magnetic Materials Indium tin oxide 0103 physical sciences Optoelectronics Thin film 0210 nano-technology business Layer (electronics) Chemical bath deposition Visible spectrum |
| Zdroj: | Solar Energy Materials and Solar Cells. 186:227-235 |
| ISSN: | 0927-0248 |
| DOI: | 10.1016/j.solmat.2018.06.025 |
| Popis: | Critical avenues to increase energy yield for CdTe photovoltaic (PV) technology, such as bifacial cells or tandem cells designs, rely on the need to develop transparent back contact approaches that enable high efficiency and high transparency. We report the properties of earth-abundant p-type transparent conducting nanocomposite (NC) thin film (CuS)x(ZnS)1-x, deposited by low-cost chemical bath deposition method. Nanocomposite films of ~ 45 nm thickness transmit > 70% of the visible light and show compact grains of size ~ 10 nm. We investigate the photovoltaic performance of both opaque and semi-transparent CdTe solar cells using (CuS)x(ZnS)1-x NC thin films as a back contact interface layer. Introduction of the NC layer between the CdTe and a standard Cu/Au metallization process yielded the best device efficiency of 13%, representing a 3.2% relative improvement over the standard Cu/Au back contact. Semi-transparent CdTe devices finished with an indium tin oxide (ITO) layer allowed for comparison of front and back illumination schemes. Experimental and modeling results confirm that the bifacial device configuration leads to significant recombination losses under back illumination due to the absence of a charge separating field, a relatively high interface recombination rate, and an insufficient electron diffusion length. Once optimized, and with an improved interface and bulk CdTe carrier lifetimes, this NC earth-abundant transparent conductor based on Cu, Zn, and S may serve as an effective, inexpensive, low-toxicity back contact layer for a bifacial CdTe solar cell. |
| Databáze: | OpenAIRE |
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