Enhanced efficiency, photocurrent and device stabilities of guanidinium chloride-based double cation mixed halide perovskite solar cells fabricated under humid conditions

Abstract

Investigations on the guanidinium chloride-included double cation mixed halide (DCMH) perovskite solar cells (PSCs) at ambient condition were performed. A modified two-step vapour deposition technique was employed for the fabrication of guanidinium [GU; C(NH2)3]-incorporated methylammonium lead iodide (MAPI) under humid conditions (RH = 65–75%). The two-step deposition was performed via methylammonium iodide (MAI) vapour treatment on GUPbI3−xClx (x = 1) perovskite film. The X-ray diffraction (XRD) patterns indicate the presence of secondary peaks corresponding to GUPbI3−xClx (x = 1) along with MAPI, and the left-shift of the characteristic (110), (220) and (310) peaks confirmed the inclusion of GU cation. The MA-GUPbI3−xClx (x = 1) film showed better morphology, with smooth surface and large grain size (∼1 μm). The device characteristics showed that the two-step deposited MA-GUPbI3−xClx (x = 1) exhibited an efficiency of PCEmax = 17.03 ± 0.44% which was higher than the conventional MAPI (PCEmax = 15.64 ± 0.32). The photocurrent stability of the MA-GUPbI3−xClx (x = 1)-based PSC was found to be better than MAPI. The guanidinium included MAPI-based PSC retained around 90% of its pristine PCE after continuous illumination for 350 h, while the PCE of MAPI-based PSCs deteriorated with the illumination time.