Alternative approach for efficient hole transporting electrode by depositing MWCNT layer on CZTS-MWCNT material for perovskite solar cell application

Abstract Metal electrode contact (i.e., Al, Ag, and Au) used for charge collection at perovskite solar cells (PSCs) needs an alternative replacement due to their expensive processing cost. Chemically reactive organic hole-transporting material (HTM) easily exposes corrosion threat to these metal electrode contacts at the Metal/organic-HTM junction. Including these two critical factors, PSC also faces a challenging issue of interface instability at perovskite/organic HTM junction. Therefore, in this work, metal contact has been replaced by Multi-wall Carbon Nanotube (MWCNT) with a simple drop-casting deposition process, and inorganic semiconductor material Cu2ZnSnS4 (CZTS) has been applied as HTM by spin coating technique. However, to improve the efficiency of PSC, CZTS-MWCNT composite has been used here as HTM due to its significant optoelectronics properties. These materials CZTS, MWCNT, and CZTS-MWCNT composites have been synthesized and characterized by XRD, FESEM, TEM, UV–Vis, and Raman spectroscopy, respectively. The fabrication process of the regular (n-i-p) structured PSCs has been described, and the photovoltaic performances have been investigated by their current-voltage characteristics. It has been observed that MWCNT embedded composite HTM (i.e., CZTS-MWCNT) has not only successfully delivered 7.60% PCE but also improved the stability of the PSC.