Researchers at China's Ludong University have developed a bio-inspired interfacial engineering strategy that leverages trans‑urocanic acid (UCA), a naturally occurring skin component, to simultaneously enhance the efficiency and stability of carbon-based, hole-transport-layer-free perovskite solar cells (PSCs).
Perovskite solar cells' commercialization remains limited by poor operational stability - particularly under prolonged light exposure and ultraviolet (UV) irradiation. This issue is especially pronounced in carbon-based, HTL-free architectures, where the absence of a hole transport layer removes an inherent UV-filtering barrier and exacerbates interfacial recombination losses. To address these limitations, the team introduced UCA as a multifunctional modifier at the buried interface. The molecule operates through a dual mechanism that combines dynamic photoprotection with static defect passivation.
The first function arises from UCA’s reversible photoisomerization. Under UV illumination, trans‑UCA converts to its cis form, effectively acting as a dynamic UV filter. This process mimics its biological role in human skin, where it protects against UV-induced damage. In the solar cell, this reversible transformation enables continuous, adaptive shielding of the perovskite layer, reducing light-induced degradation before it occurs.
At the same time, UCA provides a second, static function through its Lewis acid–base groups. These chemical functionalities interact with the perovskite surface to regulate crystallization and passivate interfacial defects. This reduces non-radiative recombination losses and improves charge extraction efficiency - two critical bottlenecks in HTL-free device architectures.
The combination of these effects - dynamic UV filtering and permanent defect passivation - creates a synergistic improvement in both device robustness and performance. Importantly, this approach avoids the trade-offs seen in earlier strategies, where additives either reacted only after degradation occurred or negatively impacted crystallinity and charge transport when incorporated into the bulk.
As a result, the UCA-modified devices achieved a champion power conversion efficiency of 18.92%. In addition, they demonstrated strong operational durability, retaining over 90% of their initial performance after 800 hours of continuous visible-light soaking.
This work highlights a new direction for perovskite interface design, showing that bio-inspired molecules can deliver adaptive protection while simultaneously optimizing electronic properties - an important step toward more durable, high-performance perovskite photovoltaics.
