The Investigation of Photovoltaic and Electrical Properties of Bi Doped CTS/Si Hetero-Junction Structure for the Solar Cell Application

Abstract

In this study, we have produced Cu-Sn-S (CTS) and Bi doped CTS powder composite structures by mixing CuS and SnS2 powders and adding %3 Bi into CuS-SnS2 (1:1) powder mixture. These raw powders were mixed and milled by a ball milling device and then CTS and Bi doped CTS target pellets have been produced by cold pressing using a mold prepared in special dimensions. The morphology and crystal structure of target pellets have analysed by SEM and XRD techniques. The target pellets contain different crystalline phases such as: Cu2SnS3, Cu2Sn3S7, Cu4Sn7S16 and SnS. It has been experienced that Bi doped CTS target pellet has better morphology compared to CTS target pellet. Using PLD technique, the target pellets have been ablated by laser beam to deposited thin film on soda lime glass substrates. According to AFM analysis, the particle size that forms Bi doped CTS thin film is larger than that of CTS thin film. Bi doped CTS thin film has poor crystal structure, while the pure CTS thin film were amorphous. The band gap of Bi doped CTS thin film is slightly lower than that of CTS thin film. While the produced Ag/CTS/Si/Al hetero-junction has not shown diode feature, Ag/Bi dop CTS/Si/Al hetero-junction has exhibited photovoltaic behaviour. The ideality factor, the barrier height, serial resistivity of Ag/Bi dop CTS/Si/Al hetero-junction have been calculated by the conventional J-V, Cheung-Cheung and Norde methods in the darkness and under the illumination (AM 1.5 solar radiation in 80 mW/cm2). The photovoltaic parameters of the hetero-junction have been determined and interpreted in detail in this article.