Synthesis of novel counter electrode by combination of mesoporous–macroporous CZTS films for enhanced performance of quantum-dots sensitized solar cells

This present study aims to manifest the potential of CZTS films as a low-cost counter electrode (CE) in quantum-dots sensitized solar cells (QDSSCs). Hitherto, numerous researchers have reported the application of either CZTS nano particles or films as a counter electrode in dye sensitized solar cells. However, its use in QDSSCs is scarcely reported. Herein, CdS quantum-dots sensitized ZnO film is used as photoanode. In the beginning, as a counter electrode, two different CZTS films (mesoporous and macroporous) are prepared using two different deposition techniques (spray pyrolysis and spin coating, respectively). For the meso-CZTS film, high V_OC and FF are observed, whereas, for the macro-CZTS film, high J_SC is observed. Hence, to take the advantage of both, subsequently, a film (meso–macro-CZTS) comprising mesoporous film upon the macroporous film is prepared and applied as CE. For the meso–macro-CZTS, substantial enhancement in power conversion efficiency (PCE) is observed. Additionally, to compare the results with commonly reported CEs (SnS/FTO and Pt–FTO) are also applied in QDSSCs. Moreover, to improve the PCE combination of these CEs along with meso–macro-CZTS, for instance, CZTS/SnS/FTO and CZTS/Pt–FTO are also applied as CE. The highest efficiency of 4.34% is achieved with CZTS/Pt–FTO.