Reduction of extrinsic defects in ZnSe:perovskite composites based solar devices

This study presents the synthesis of ZnSe nanoparticles (NPs) via precursor solution method; preparation of perovskite and ZnSe:perovskite composites (0, 2, 4, and 6 mg/ml, respectively) via solution processing method. The synthesis of these materials has been confirmed by X-ray diffraction/XRD, UV–Visible spectroscopy, steady-state photoluminescence (PL) spectroscopy, time-resolved photoluminescence (TRPL) spectroscopy, contact angle analysis and scanning electron microscopy/SEM. As-synthesized ZnSe:perovskite composites have been deployed in the fabrication of solar cells. SEM micrographs of these composites have shown a significant reduction in extrinsic defects of perovskite films on incorporation of ZnSe NPs into perovskites matrices indicating improvement in morphology. The contact angle analysis confirmed a significant decrease in the hydrophilicity as contact angle is increased by ~ 10° as compared to that of pristine perovskite. Moreover, TRPL spectroscopy confirmed a modest increase in the lifetimes and hence, reduction in the recombination rate within ZnSe:perovskite composites. Likewise, J-V curve of as-fabricated devices demonstrates an improvement in the performance with the increase in the concentration of ZnSe NPs into perovskite. The best device based on these composites has shown an efficiency of 5.98%, open circuit voltage/V_oc of 0.931 V, short circuit current density/J_SC of 9.82 mA/cm² and fill factor/FF of 65.50% which has retained 79.6% of its actual efficiency after 30 days of air exposure.