Abstract
Abstract
A promising way to advance perovskite solar cells is to improve the quality of the electron transport material – e.g., titanium dioxide (TiO2) – in a direction that increases electron transport and extraction. Although dense TiO2 films are easily grown in solution, efficient electron extraction suffers due to a lack of interfacial contact area with the perovskite. Conversely, mesoporous films do offer high surface-area-to-volume ratios, thereby promoting efficient electron extraction, but their morphology is relatively difficult to control via conventional solution synthesis methods. Here, a pulsed laser deposition method was used to assemble TiO2 nanoparticles into TiO2 hierarchical nanoarchitectures having the anatase crystal structure, and prototype solar cells employing these structures yielded power conversion efficiencies of ~ 14%. Our approach demonstrates a way to grow high aspect-ratio TiO2 nanostructures for improved interfacial contact between TiO2 and perovskite materials, leading to high electron-hole pair separation and electron extraction efficiencies for superior photovoltaic performance. Compared to conventional solution-processed TiO2 films that require 500 oC to obtain a good crystallinity, our relatively low temperature (300 oC) TiO2 processing method may promote reduced energy-consumption during device fabrication as well as enable compatibility with various flexible polymer substrates.
