Chiral ligand-assisted interface modulation for reduced voltage loss in perovskite solar cells

Perovskite solar cells (PSCs) have emerged as strong contenders for next-generation photovoltaic applications, owing to their exceptional optoelectronic characteristics and adjustable bandgaps. Despite these advantages, a notable discrepancy persists between the theoretical and experimentally achieved open-circuit voltage (Voc), largely attributed to interfacial energy misalignment and non-radiative recombination processes. In this work, we propose the introduction of chiral organic compounds into the perovskite precursor solution as a means to tailor the electronic structure and interfacial behavior of the absorber layer. Our systematic study reveals that the integration of chiral ligands not only promotes improved crystallinity of the perovskite films but also modulates lattice microstrain, as evidenced by X-ray diffraction (XRD) and microstrain analysis. Electrochemical impedance spectroscopy (EIS) results further indicate a reduction in charge transport resistance and interfacial recombination, confirming a more favorable electronic interface between the perovskite and charge transport layers. Importantly, the non-radiative voltage loss is significantly mitigated, decreasing from 354 mV in the control to 304 mV with chiral additive incorporation, thereby yielding an average Voc of 1.16 V. This study underscores the effectiveness of chiral molecular engineering in tuning film quality and interface properties. It also demonstrates a scalable strategy for enhancing PSC device efficiency, offering a promising pathway to close the Voc gap and advance perovskite-based photovoltaics toward greater performance and long-term operational stability.