Suppression of pinhole defects in thin film CdS/CdTe solar cell via gelatin-based negative photoresist passivation

• Published in: Materials science in semiconductor processing Vol. 148; p. 106817
• Main Authors: Liu, Hongjiang, Zhou, Yufeng, Xie, Qiaomu, Wang, Gang, Jiang, Meng, Pan, Jingong, Wang, Ruilin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.09.2022
• Subjects: CdS/CdTe; Cu doping; Gelatin-based negative photoresist; Pinhole; Solar cell; Solar cell; CdS/CdTe; Pinhole; Cu doping; Gelatin-based negative photoresist
• ISSN: 1369-8001; 1873-4081
• DOI: 10.1016/j.mssp.2022.106817

The existence of pinholes at the CdS/CdTe and CdTe/back contact interfaces is one of the main obstacles to achieve high power conversion efficiency (PCE) in thin film CdS/CdTe solar cells, which leads to the formation of shunt paths in the devices. In this paper, a gelatin-based negative photoresist (Gel-NP) is utilized to fill the pinhole defects of CdTe thin film in photovoltaic device with FTO/CdS/CdTe/Mo/Al/Cr structure. The results showed that the pinholes in CdTe thin film have been effectively filled via the passivation of the Gel-NP, and no residue was found on the surface of CdTe thin film, thus increasing the cell shunt resistance. In addition, the optoelectronic performance of CdS/CdTe thin film solar cell under different Cu diffusion concentrations have been investigated with and without Gel-NP treatment, in which Gel-NP passivates the surface of CdTe resulting in a large amount of Cu enriched on the back, forming CuxTe after annealing. As a result, the average PCE of FTO/CdS/CdTe/Mo/Al/Cr structured solar cell increased from 10.4% to 13.7% via Gel-NP passivation (14.1% of champion efficiency), which exhibits improved reproducibility as well. •Gelatin-based negative photoresist (Gel-NP) can selectively fill pinholes on the CdTe surface.•Gel-NP passivates the surface of CdTe resulting in a large amount of Cu enriched on the back, forming CuXTe.•The average power conversion efficiency of CdS/CdTe solar cell increased from 10.4% to 13.7% via Gel-NP passivation.•The Gel-NP passivation increased the reproducibility of cell performance.•The Gel-NP passivation can help to improve the power conversion efficiency of industrial large-area cells.