Modeling of a high performance bandgap graded Pb-free HTM-free perovskite solar cell

In this study, a lead-free nontoxic and hole transport material (HTM)-free perovskite solar cell (PSC) with a novel configuration of glass/FTO/ZnO/CH3NH3SnI3-xBrx/back contact has been modeled and optimized by a solar cell capacitance simulator (SCAPS). The bandgap of CH3NH3SnI3-x,Br-x absorber is tuned in the range of 1.3 eV to 2.15 eV by variation of the Br doping content. To make a comparison, an optimized Pb based PSC is also modeled. By optimizing the parameters, power conversion efficiency (PCE) of 16.30%, open circuit voltage (V-oc) of 1.02 V, short circuit current density (J(sc)) of 22.23 mA/cm(2), and fill factor (FF) of 0.72 were obtained. As compare to the reports available in the literature, these results show much improvement and can provide guidelines for production of economic and environmentally friendly PSCs with further efficiency enhancement.