Efficient Planar Perovskite Solar Cells with Entire Low-Temperature Processes via Brookite TiO2 Nanoparticle Electron Transport Layer

Abstract

Electron transport layer (ETL) is well known as a crucial factor that affects power conversion efficiency (PCE) of perovskite solar cells (PSCs). Low temperature process on ETL has been highly considered for the future of low cost and roll to roll process in mass production of PSCs industrialization. Herein, we demonstrate the low-temperature ( 2 nanoparticle (BK TiO 2 NPs) layer as an ETL of PSCs, followed by different concentrations of TiCl 4 treatment (20mM, 40mM, 60mM and 80mM). By using BK TiO 2 NPs with the low temperature process ( 2 NPs layer is a new candidate of ETL that can be fabricated in low temperature processes. The optimized TiCl 4 concentration is 40mM for the surface treatment of BK TiO 2 NPs, which results in the enhancement of PCE, reproducibility and the supression of hysteresis. Probably, the 40mM of TiCl 4 treatment improves the interface between the perovskite and BK TiO 2 NPs layers and promotes the efficient charge extraction. Thus, the present work is expected to provide an important technology to realize the low-cost planar PSCs produced in entire low-temperature processes.