Vanadium Oxide Post-Treatment for Enhanced Photovoltage of Printable Perovskite Solar Cells

Printable perovskite solar cells (PSCs) have attracted widespread attention due to the simple fabrication process and low-cost raw materials. However, because no hole transport material is used and the carbon layer possess a relatively low work function of only 4.8–5.0 eV, a significant potential loss exists in printable PSCs, resulting in a relatively low open-circuit voltage (VOC). We employed vanadium oxide (VOx) to post-treat the interface of carbon/perovskite, and effectively enhanced the photovoltage and PCE of printable PSCs. VOx possesses a high work function of ∼5.39 eV, and thus can facilitate the charge transfer from perovskite to carbon due to a more favorable energy level alignment. The VOC of the devices can be enhanced from ∼892.73 to ∼922.86 mV, delivering an average PCE of 14.47% and a champion PCE of 15.77%. In addition, this post-treatment method can also suppress the hysteresis of printable PSCs. The hysteresis index was reduced from 0.025 to −0.001 with VOx treated cells. This VOx post-treatment method is simple, easy to operate and compatible with various perovskite absorbers in printable PSCs, providing a promising prospect for further applications.