Perovskite solar cells have leapt forward in efficiency in part because self-assembled monolayers (SAMs) can be grown on transparent conductive oxides such as TCO-coated indium tin oxide (ITO). By anchoring to the oxide surface, these ultrathin layers create an interfacial molecular dipole that extracts electrons more efficiently from the perovskite absorber. Yet the very mechanism that enables charge extraction also exposes a major weakness: the bonding between typical SAM anchor groups and oxide surfaces can be intrinsically weak. Under operational stress—heat, light, and thermal cycling—this fragility can trigger desorption, undermining long-term performance and stability.
A research team now reports a strategy to make SAMs far more resilient by redesigning their molecular electronic structure. Instead of relying only on conventional phosphonic acid–to-ITO binding, the authors build a donor–acceptor–donor (D–A–D) resonant architecture. In this design, electronic resonance concentrates negative charge density at the acceptor anchoring motif, effectively strengthening the chemical interaction with the ITO surface.
The stability results are striking. Devices incorporating the resonant SAM show negligible efficiency decay during maximum-power-point tracking (MPPT) for 1,080 hours at 85 ± 5 °C. Under additional stress from metal halide lamp illumination—100 mW cm⁻² with 4.4% UV content—at the same elevated temperature, the cells maintain more than 93% of their initial performance after 1,080 hours. Thermal robustness also improves: the devices retain over 98% after 720 repetitive temperature cycles spanning −40 °C to 85 °C.
The work links stability to charge transport, not just adhesion. Resonance-induced charge delocalization is proposed to improve carrier transport across the interface, reducing bottlenecks that typically accompany molecule–oxide layers. As a result, the interfacial layer functions simultaneously as a stabilizing anchor and as a facilitator of efficient electron extraction.
On the performance side, the approach scales to different device formats. The team reports certified power conversion efficiencies (PCEs) of 27.69% for 0.063 cm² devices and 23.63% for a larger aperture area of 15.64 cm². These figures place the method among the most competitive stability-focused interfacial engineering strategies in perovskite photovoltaics.
Importantly for commercialization relevance, the resonant SAM concept also transfers to flexible substrates. A certified efficiency of 26.64% is demonstrated on flexible devices of 0.063 cm², suggesting that the molecular resonance strategy does not depend narrowly on rigid device architectures.
Overall, the study frames a new stability paradigm for perovskite solar cells: tune the SAM’s electronic resonance to boost negative charge at the binding site, thereby reinforcing anchoring chemistry while simultaneously enhancing interfacial electronic transport. If broadly generalizable, resonant molecular design could become a key ingredient in reliable, high-efficiency perovskite modules.
Subject of Research: Stability-enhanced self-assembled monolayers for perovskite solar cells (electron extraction and reduced SAM desorption)
Article Title: Electronic-resonance enhanced molecule for perovskite solar cells
Article References: Wu, X., Kou, W., Li, Z. et al. Electronic-resonance enhanced molecule for perovskite solar cells. Nature (2026). https://doi.org/10.1038/s41586-026-10919-4
Image Credits: AI Generated
DOI: 10.1038/s41586-026-10919-4
Keywords: self-assembled monolayers; perovskite solar cells; donor–acceptor–donor resonance; phosphonic acid; ITO anchoring; charge extraction; operational stability; maximum power point tracking
