Comparison of Optimum Zno : Al Sputter-Deposition Temperature for Cu(In,Ga)Se2 Photovoltaic Absorbers Prepared by Two Conventional Methods: Elemental Co-Evaporation and Selenization of Sputtered Metal Precursor
Heterojunction Cu(In, Ga)Se2 (CIGS) solar cells comprise a substrate/Mo/CIGS/CdS/i-ZnO/ZnO:Al. Here, Al-doped zinc oxide (AZO) films were deposited by magnetron sputtering, and the substrate temperature was optimized for CIGS solar cells with two types of CIGS light absorbers with different material properties fabricated by 3-stage co-evaporation and 2-step metallization followed by sulfurization after selenization (SAS). The morphologies, electrical and optical properties, and microstructures of the fabricated AZO thin films (at different substrate temperatures, 150–550 °C) were characterized, and their effects on the CIGS solar cell performance were systematically investigated. X-ray diffraction results confirmed a hexagonal crystal structure with a (002) preferred orientation for all the deposited AZO films. The optical and electrical properties of the AZO films improved significantly with increasing substrate temperature. Photovoltaic performances of the two types of CIGS solar cells were influenced by changes in the AZO substrate temperature. For the 3-stage co-evaporated CIGS cell, as the sputter-deposition temperature of AZO layer increased from 150 °C to 550 °C, the efficiencies of CIGS devices decreased monotonically, which suggests the optimum AZO deposition temperature is 150 °C. In contrast, the cell efficiency of CIGS devices fabricated using the 2-step SAS- processed CIGS absorbers improved with increasing AZO deposition temperature from 150 to 350 °C. However, further increase in AZO deposition temperature to 550 °C decreased the cell efficiency, indicating that the optimum AZO deposition temperature was 350 °C. The findings of this study provide insights for the efficient fabrication of CIGS solar cells considering the correlation between CIGS absorber characteristics and AZO layer deposition temperature
Year of publication: |
[2022]
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Authors: | Park, Hyeonwook ; Alhammadi, Salh ; Minnam Reddy, Vasudeva Reddy ; Park, Chinho ; Kim, Woo Kyoung |
Publisher: |
[S.l.] : SSRN |
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