Compact TiO₂/Anatase TiO₂ Single-Crystalline\nNanoparticle Electron-Transport Bilayer for Efficient Planar Perovskite\nSolar Cells

Abstract

Electron-transport\nlayer (ETL)/perovskite interface modification\nplays a key task for producing efficient planar perovskite solar cells\n(PSCs). In this study, interfacial modification of compact TiO₂ using novel, one-step hydrothermally synthesized single-crystalline\nanatase (AT) titania nanoparticles (TiO₂ NPs) (average\ndiameter = 6–10 nm) was applied as an ETL bilayer to enhance\nthe efficient charge generation and extraction and eliminate the electron–hole\nrecombination ratio. We report here an easy approach for enhancing\nthe performance of planar PSCs by introducing a compact TiO₂/AT TiO₂ NPs bilayer through spray pyrolysis (SP) deposition\nand spin-coating (SC) techniques, respectively. The enhanced performance\nof the devices with an SP-TiO₂/SC-AT TiO₂ NPs\nbilayer facilitated more efficient electron transport, charge extraction,\nand low interfacial recombination. Ultimately, the best device had\na 17.05% power conversion efficiency resulting from the significant\ndecrease in <i>J–V</i> hysteresis, presenting almost\na 12% performance improvement compared to the TiO₂ only\nlayer-based counterpart. Thus, the present study provides an important\nadvance to the design of photovoltaic devices with respect to charge\ntransport and electron–hole recombination.