Interface engineering of organic hole transport layer with facile molecular doping for highly efficient perovskite solar cells

Energy level and the charge extraction/transportation ability of the hole transport layer (HTL) have significant impacts on the photovoltaic (PV) parameters of the perovskite solar cell (PSC) devices. A doping process has been one of the representative works to manage these characteristics, but the solution-blend doping, widely applied to the organic semiconductor HTL, has shown limited processability. In this work, we design a facile interfacial doping process for poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) HTL in p-i-n structure PSC device. This approach provides superior optical and electrical properties to the PTAA layer, even with better processability, and its proper hydrophobicity is beneficial to forming pinhole-free perovskite even with superior crystallinity and reduced trap density. Moreover, the dipole layer localized at the interface with the perovskite enhance the built-in potential of device, improving its carrier transportation. As a result, this approach largely enhances the efficiency of the p-i-n PSC device from 18.06% (blend-doping) to 20.67% with superior stability preserving 94% of its initial efficiency after 500 h under ambient air.

Automated summary

This study proposes a facile interfacial doping process for the hole transport layer (HTL) of perovskite solar cells (PSC), which significantly improves the optical and electrical properties of the HTL, enhances the processability and hydrophobicity of the material, and increases the built-in potential of the device. As a result, the efficiency of the p-i-n PSC device is greatly enhanced, reaching 20.67% with superior stability.