Solution processed earth abundant copper iron/manganese tin sulphide thin films for photovoltaic applications

Abstract

This work focuses on earth abundant Cu2(Fe,Mn)SnS4 (C(F,M)TS) thin films for solar absorber materials. Synthesis of C(F,M)TS by a simple non-toxic spray pyrolysis technique is reported. X-Ray diffraction and Raman spectroscopy confirm the presence of C(F,M)TS in the thin films after sulphurization. CFTS and CMTS exhibited band gaps, carrier density and carrier mobility similar to CIGS and CZTS. CFTS was employed as a counter electrode in dye-sensitized solar cells (DSSCs) and exhibited good conversion efficiencies (8.03%). A photovoltaic device with a structure of Mo/CMTS/CdS/TCO/top electrode was fabricated as a proof-of-concept and yields a preliminary power conversion efficiency of ~ 0.2%. Through analyses of the device characteristics we identify a key problem of very high carrier density in the CMTS absorber that leads to short collection length, low Voc, low quantum efficiency at long wavelength and high shunt conductance that quench the fill factor.