Solar cells built using the technique achieved a certified power conversion efficiency of 25.61 per cent, independently verified by the Solar Energy Research Institute of Singapore.
Perovskite solar cells have attracted significant research interest because they are cheaper and easier to manufacture than conventional silicon-based panels. Their commercial potential has been limited, however, by questions over how well they hold up under the heat and humidity conditions of real-world deployment. Under accelerated ageing tests, the treated material required roughly twice the thermal energy to degrade compared with comparable materials reported in recent literature - a meaningful improvement in a field where long-term stability is the central challenge.
Dr Jae Sung Yun, co-author of the study and nanoscale imaging expert from the University of Surrey's Advanced Technology Institute, said: "Perovskite solar cells could genuinely change how we generate electricity - they are cheaper to make than silicon panels and the efficiency numbers are now very competitive. The stumbling block has always been durability. What I find exciting about this work is how elegantly simple the solution turns out to be. You place two films in contact, and that contact alone reorganises the material at a molecular level confirmed by our state-of-the-art nanoscale chemical imaging techniques - all the way through, not just at the surface. No extra chemicals, no added complexity."
The technique works through what the researchers call contact-triggered cationic interaction (CCI). When two perovskite films are placed in physical contact, molecular forces at the interface cause the charged particles - cations - within the light-absorbing layer to adopt a more uniform, aligned arrangement. This reduces the structural defects that cause energy to be lost as heat rather than converted to electricity. The time that charge carriers survive before recombining - a key measure of solar cell quality - increased from 4.48 to 5.89 microseconds in treated material compared with untreated controls.
To confirm the molecular changes, the Surrey team used photo-induced force microscopy (PiFM), a technique that maps chemical signatures at the nanoscale by combining the high resolution of atomic force microscopy with infrared spectroscopy, bypassing the diffraction limit of light. This allowed the researchers to visually validate the precise, uniform formation of chemical bonds triggered by the CCI process, confirming that the molecular alignment occurred exactly as predicted at the film interface.
Professor Ravi Silva, Director of the Advanced Technology Institute at the University of Surrey, said: "What this study demonstrates is that you can meaningfully improve both the efficiency and the durability of perovskite solar cells without adding a single extra chemical or processing step - just by controlling how two films interact at the point of contact. That is a genuinely elegant result, and the performance numbers back it up. This kind of advance matters because stability under real-world conditions is the central challenge the field has to solve before perovskites can be deployed at scale."
Research Report:Contact-triggered molecular interactions enable structural refinement of perovskite layers in solar cells
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