Buried interface engineering enables efficient and refurbished CsPbI3 perovskite quantum dot solar cells

Abstract

Interfacial engineering has proven to be extremely important for colloidal quantum dot (QD) solar cells. However, in comparison with the QD surface and device top interface, the buried interface has received much less attention. Herein, we report an efficient strategy of utilizing a cyclic passivator (CyP), namely, acesulfame potassium, to modulate a titanium oxide (TiO₂)/CsPbI₃ QD buried interface. The isotropic CyP can effectively passivate defects at the TiO₂ and CsPbI₃ QD surface through target chemical binding and, hence, facilitate interfacial charge extraction and transport. Substantially, the CyP-engineered buried interface delivers a high power conversion efficiency (PCE) of 17.50% for all-inorganic CsPbI₃ perovskite QD solar cells. More importantly, we first report the refurbishment of high-efficiency QD solar cells, and CyP-buried modulation can assist in the recycling of high-cost TiO₂/F-doped tin oxide electrodes. The PCE of the CyP-engineered refurbished CsPbI₃ QD device remains over 90% of the corresponding fresh one after up to the 4th round of recycling of retired devices. These findings reveal the importance and potential of the buried interface that will propel both the performance and sustainable development of QD-based optoelectronic devices.