Low temperature synthesis of hierarchical TiO2nanostructures for high performance perovskite solar cells by pulsed laser deposition.
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 TiO2films are easily grown in solution, efficient electron extraction suffers due to a lack of interfacial contact area with the perovskites. 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 TiO2nanoparticles into TiO2hierarchical architectures exhibiting an 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 TiO2nanostructures for improved interfacial contact between TiO2and perovskite materials, leading to high electron-hole pair separation and electron extraction efficiencies for superior photovoltaic performance. Compared to previous pulsed laser deposition-synthesized TiO2mesoporous crystalline networks that needed post-thermal annealing at 500 °C to form mesoporous crystalline networks, our relatively low temperature (300 °C) TiO2processing method may promote reduced energy-consumption during device fabrication, as well as enable compatibility with flexible polymer substrates such as polyimide.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. xiaok@ornl.gov.
Bin
B
Yang
Masoud
M
Mahjouri-Samani
Christopher M
CM
Rouleau
David B
DB
Geohegan
Kai
K
Xiao