Morphology modulated brookite TiO2 and BaSnO3 as alternative electron transport materials for enhanced performance of carbon perovskite solar cells

Abstract

Designing alternatives to TiO2 electron-transport layers (ETLs) for facile electron extraction and transport to enhance the efficiency of n-i-p structured carbon perovskite solar cells (CPSC) is still a less explored research interest. In this work, the combined effect of the phase and morphology of BaSnO3 (BSO) and brookite TiO2 (BTO) nanostructured materials are explored as alternative electron transport layers (ETLs) instead of dominating anatase TiO2 in CPSC. The highest power-conversion efficiencies (PCEs) of CPSCs with rod-shaped BTO and BSO were recorded at ∼15.02% and ∼13.4%, respectively, which claims the highest efficiency for BTO and BSO CPSCs in ambient conditions to the best of our knowledge. In addition, our findings indicate that the CPSC's with rod structured BTO and BSO exhibited decreased charge recombination and improved efficiency compared to concerning spherical morphologies (12.5% for BSO nanoparticles) and cubic particles (14% for BTO nanocubes) due to the superior photogenerated charge-carrier extraction and enhanced interface quality. This research will open the door for various morphologies of alternative ETL materials and their physicochemical understanding toward achieving high-efficiency ambient CPSCs.