Efficient and Ambient-Air Processed Perovskite Solar Cells Enabled by Adamantanethiol as a Dual-Action Modulator

This work presents a dual-modulation strategy using 1-adamantanethiol (ADT), a rigid cage-like molecule, to simultaneously enhance the efficiency and stability of inverted perovskite solar cells. In contrast to conventional flexible small molecule modulators, ADT features a highly rigid three-dimensional adamantane skeleton that enables the formation of a stable steric barrier layer on the perovskite surface. Meanwhile, its terminal -SH group exhibits strong coordination affinity with undercoordinated Pb²⁺ ions, providing effective chemical passivation of surface defects. Beyond defect healing, the ADT treatment further modulates the interfacial energy-level alignment and optimizes charge carrier extraction and transport, as systematically verified by a suite of advanced optical characterizations, including transient absorption (TA) spectroscopy and terahertz time-domain spectroscopy (THz-TDS). Taken together, these techniques confirm accelerated carrier dynamics and suppressed recombination losses upon ADT passivation. All solution-processing steps were conducted in ambient air (20-25 °C, 40-60% RH), where the hydrophobic ADT layer protects the perovskite from moisture. As a result, the inverted perovskite solar cells fabricated entirely in ambient air incorporating ADT achieve a power conversion efficiency of 23.9%, alongside significantly enhanced operational stability, as evidenced by maintaining superior performance during 400 h of maximum power point (MPP) tracking under continuous illumination.