Carrier transport and surface potential over phase variations in the surface and bulk of highly efficient Cu2ZnSn(S,Se)(4) solar cells

Abstract

We report highly efficient Cu2ZnSn(S,Se)4 (CZTSSe) thin films with a power conversion efficiency (PCE) of 12.3% at their surface and interface. The structural and electrical properties were locally investigated, using scanning probe microscopy and micro-Raman scattering, to improve the performance of kesterite solar cells. Interestingly, this research reports quite different results from the conventional kesterite solar cells, owing to the observance of undesirable voids and secondary phases. Nonetheless, the solar cells exhibit a high PCE of over 12%. Thus, we probe the kesterite solar cells as a function of the depth and introduce a mechanical dimple-etching process. The relatively low melting temperature of the pure-metal precursors results in the unique properties within the solar cell materials. Understanding these phenomena and their effects on carrier behavior enables the achievement of a higher PCE and better performance for kesterite solar cells. © 2020 John Wiley & Sons, Ltd.