Planar perovskite solar cells: eco-friendly synthesized cone-like ZnO nanostructure for efficient interfacial electron transport layer

Abstract

The process of interfacial engineering in planar perovskite solar cells (PPSCs) plays an important role not only in transferring charges from active perovskite layer but also in enhancing the device performance. Considering this, the present study aims to synthesize an eco-friendly solution processed ZnO nanostructure interfacial electron transport layer (ETL) in PPSCs. The optical, structural, morphological and chemical properties of the prepared ZnO nanostructured material are analysed using ultraviolet–visible spectroscopy (UV–Vis), X-ray diffraction analysis (XRD), field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analysis, respectively. Under ambient conditions, the device performance in terms of efficiency, stability and device degradation are investigated for both single layer (c-TiO2 and cone-like ZnO nanostructure) and bilayer (c-TiO2/cone-like ZnO nanostructure) ETL. Furthermore, the effective way of constructing cone-like nanostructured ZnO ETL on top of c-TiO2 surface, found to be improved in faster charge transfer at the ETL/perovskite interfaces and reduced recombination losses. As a result, it exhibits maximum power conversion efficiency (PCE), short-circuit current density, fill factor and open-circuit voltage as 8.02%, 15.33 mA cm−2, 0.52% and 0.99 V, respectively. Besides, the stability of PPSCs fabricated with bilayer exhibits better air stability of\u2009~\u200987.40% with retained rate of 250 h from its initial value.