Development of Cu2SnS3 (CTS) thin film solar cells by physical techniques: A status review

Abstract

Developments in thin film solar cell technology have attracted major attention in the recent years due to its capacity to reliably satisfy the required energy needs. Various solar absorber compounds such as CdTe, CuInGaS (CIGS), CIGSSe and Cu2ZnSnS4 (CZTS) have been employed for solar cell fabrication. The elemental toxicity, scarcity and complex structure due to more number of elements in these compounds restrict their use in future photovoltaic applications. Cu2SnS3 (CTS), a ternary semiconductor compound compromised of nontoxic and earth abundant elements is emerging as photovoltaic material and preferably employed for solar cell application due to its optimal structural and optical properties. The power conversion efficiency (PCE) based on CTS based absorber compound has been improved from 0.11% to 4.63% by developing the physical synthesis techniques which also indicating further scope for enhancement in the power conversion efficiency (PCE). The current review aims to examine the various physical techniques employed for synthesis of CTS thin films. Amongst the various physical techniques, sputtering, vacuum evaporation and electron beam evaporation techniques have showed reliable solar cell efficiency due to the production of high quality, uniform and compact thin film absorber compound. Other techniques such as solid state reaction, ball milling and pulsed laser deposition (PLD) employed for absorber compound synthesis have shown low efficiency due to the production of non-compact structure and compositional inhomogeneity. The parameters such as composition, thickness, uniformity and purity of absorber compound are the key factors that affect the performance of solar cell. Other factors such as sulfurization conditions, doping and crystallization also affect the solar cell performance. The impact of these parameters on the CTS thin film synthesis and its related solar cell performance is described. The efficiency losses in CTS solar cells and their possible remedies are discussed. Finally, the challenges and scope of the CTS solar cells are presented.