Spatially resolved opto‐electrical performance investigations of Cu₂ZnSnS_3.2Se_0.8 photovoltaic devices

Abstract

A new statistical analysis of spatially resolved photocurrent and electroluminescence images has been developed and applied to Cu2ZnSn(SxSe1−x)4 (CZTSSe) monograin solar cells. CZTSSe as an absorber material has the potential to significantly reduce manufacturing costs and develop new application fields in photovoltaics. Deep understanding of the performance related parameters in various production steps is crucial for further development of the technology. In this paper we show that by a thorough investigation by means of a combination of opto‐electrical measurement methods such as light beam induced current mapping, scanning electron microscopy, optical microscopy, photoluminescence, and electroluminescence measurements a correlation with different current‐voltage (j/V) measurement parameters can be established. Hereby, we clearly identify barrier variations at the active interface as the main reason for current variations across the cell, which for record cells can largely be avoided. These variations show up clearly in the microscopic spatial analysis developed. The detailed analysis of the homogeneity of the solar cell photocurrent presented in this study is relevant for all kinds of solar cells including thin‐film and wafer‐based cells.

Emergence of flexible kesterite solar cells: progress and perspectives

“…Therefore, the power conversion efficiency is mainly determined by the performance of the monograin unit cells and how compact the unit cells are integrated-the inner interface of polycrystalline thin film (grain boundaries) and the large area homogeneity are no longer a concern. After removing the defective surface layer by chemical etching, and ordering treatment and surface passivation by air annealing, the efficiency of the monograin CZTSSe unit cell is estimated to be ~12% 79 . While, due to the non-active area between the monograins, the overall efficiency of monograin layer CZTSSe solar cells is slightly lower than the unit cells 18,78,80,81 .…”

Emergence of flexible kesterite solar cells: progress and perspectives

“…After removing the defective surface layer by chemical etching, and ordering treatment and surface passivation by air annealing, the e ciency of the monograin CZTSSe unit cell is estimated to be ~12%. 94 While, due to the non-active area between the monograins, the overall e ciency of monograin layer CZTSSe solar cells is slightly lower than the unit cells. 18,88,89,93 One would expect that the optoelectronic quality of CZTSSe monograins should be much better than that of the CZTSSe thin lms since CZTSSe monograins are synthesised at higher temperature and the grain size is 10-100 times larger.…”

Stability, reliability, upscaling and possible technological applications of kesterite solar cells

“…Every grain is already a small solar cell, since the p-type kesterite single crystals are already coated with an n-type buffer layer (e.g. cadmium sulfide or zinc oxysulfide) [25].…”