Unlike traditional silicon panels, perovskite can be tailored to absorb the specific wavelengths from indoor lighting. However, the material's crystal structure often contains microscopic defects, or "traps", that disrupt electron flow and shorten lifespan.
In work published in Advanced Functional Materials, the team reports using a combination of chemicals to minimise these defects, producing cells about six times more efficient than the best commercial indoor solar cells. The devices are expected to last more than five years, compared with weeks or months for many prototypes.
Senior author Dr Mojtaba Abdi Jalebi said billions of small electronics rely on wasteful battery replacements and that their newly engineered perovskite cells could harvest more indoor energy at lower cost, using Earth-abundant materials and simple printing techniques.
Researchers improved crystal uniformity with rubidium chloride, reducing internal strain and trap density. Two organic ammonium salts, N,N-dimethyloctylammonium iodide and phenethylammonium chloride, stabilised iodide and bromide ions, preventing performance-degrading phase separation.
Lead author Siming Huang compared the approach to reassembling a broken cake, allowing electrical charge to flow more freely. The combined additives had a synergistic effect greater than their individual contributions.
Under 1000 lux indoor light, the cells converted 37.6% of energy into electricity - a world record for wide bandgap (1.75 eV) indoor photovoltaics. After 100 days, they retained 92% of their performance, compared to 76% for untreated devices. In harsher tests at 55oC for 300 hours, performance fell to 76% versus 47% for controls.
The work involved collaborators from the UK, China and Switzerland, with support from the Henry Royce Institute and funding from the UK's EPSRC, Department for Energy Security and Net Zero, UCL, the British Council and London South Bank University.
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