Front electric-field enabling highly efficient perovskite photovoltaics

The efficient carrier extraction and transport will be greatly aided by a proper heterojunction that has formed at the interface of perovskite photovoltaics. For n-i-p devices, the film quality of perovskites is further influenced by the characteristics of the interface between the electron transport layer (ETL) and perovskite layer. Herein, we introduce a "front surface field" based on the concept of back surface field (BSF) technique into perovskite photovoltaics. We optimize the energy band arrangement for devices by adding a potent n-type molecular buffer layer (naphthalene, 2,6-naphthalene dicarboxylic acid (2,6-NDA)) at the interface between the ETL and the perovskite layer. The generated electric filed at the interface results in more perfect interface contact and efficiently inhibits interface charge recombination, producing a high open-circuit voltage. The 2,6-NDA-treated device delivered a power conversion efficiency up to 24.19% by a reduce of the open-circuit voltage loss with 370 mV. The finding in this work provides a new route to optimize the device architectures for highly efficient perovskite photovoltaics.