Tailoring the interface by a multifunctional amphiphilic molecule enabled 24.84%-efficiency and stable perovskite solar cells

Abstract

Surface defects are detrimental to the performance and stability of perovskite solar cells (PSCs). Herein, an amphiphilic molecule of tert-butyl carbazate (TBC) with multiple functional groups is employed for interface passivation between perovskite and spiro-OMeTAD. We unveil the synergistic mechanism of a) defect-passivation of Pb-related involving coordination and chelation; b) immobilization components through three types of hydrogen bonding interactions; c) enhanced crystallinity and preferential orientation induced by crystal regrowth. These effects minimize the nonradiative recombination and inhibit ion migration. Moreover, TBC introduces a dipole interlayer that facilitates favorable and efficient hole extraction and transport. As a result, the TBC-treated PSCs exhibited a remarkable power conversion efficiency of 24.84%, higher than the control efficiency of 22.04%. Notably, the hydrophobic terminal tert-butyl group confers excellent stability upon the device. Unpackaged devices stored in open-air conditions for 1200 h, experienced only a 5.3% reduction in efficiency. They retained their initial efficiency of 82.7% following 800 h of operation under one-sun illumination in ambient conditions without encapsulation. This proposed interfacial engineering strategy using multiple anchoring groups of amphiphilic molecules presents a new approach for obtaining highly efficient and stable PSCs.