Low-temperature photochemical activation of sol-gel titanium dioxide films for efficient planar heterojunction perovskite solar cells

To realize high-performance perovskite solar cells (PSCs) ensuring low-cost flexible application with low energy consumption, efficient electron transport layers (ETL) that can be processed at low temperatures are desired. In this contribution, low temperature (about 70 degrees C) UV/ozone irradiation was applied to synthesis crystallized TiO2 films as ETL. The UV exposure induces photo-catalytic removal of the organic ligands and spontaneous coalescence of the TiO2 framework, resulting in excellent TiO2 films with considerable crystallinity. UV irradiation induces both complete removal of organic media and more efficient charge collection. Accordingly, planar heterojunction (PH) PSCs with such ETL exhibited outstanding photovoltaic performance up to 17.03%, which is even higher than the value (12.98%) of counterpart device with high temperature thermal sintered TiO2 ETL (without TiCl4 treatment). These low temperature solution-processed TiO2 films by facile UV irradiation are suitable for the low-cost, large yield solution process on a flexible substrate for photoelectric devices. (C) 2017 Elsevier B.V. All rights reserved.