Semi-Transparent Solar Windows Balance Natural Light and Power Generation
A research team at University College London (UCL) recently published breakthrough findings, successfully developing semi-transparent perovskite solar windows that maintain 30% light transmittance while achieving 14% module power conversion efficiency. This technological advancement not only enables scalable manufacturing of 30 × 30 cm modules but also opens new pathways for building-integrated photovoltaic systems. The team noted that these solar windows can effectively reduce air conditioning loads in hot climates while generating electricity, delivering dual benefits of energy savings and carbon reduction.
The UCL team optimized the perovskite layer thickness to approximately 185 nanometers and employed a molybdenum trioxide/gold/molybdenum trioxide (MoO₃/Au/MoO₃) transparent electrode, boosting electrode transmittance to 59.9%. Additionally, researchers introduced 3-trifluoromethyl-1H-1,2,4-triazole molecules, which coordinate with uncoordinated lead ions to suppress electron trap effects and stabilize the lattice structure. This design not only extended material longevity but also increased the power conversion efficiency of perovskite solar cells under indoor lighting to 22%, setting a new benchmark for comparable technologies.
Siming Huang, the study’s lead author and a Ph.D. candidate at UCL, stated that semi-transparent perovskite solar windows provide cooling benefits similar to traditional tinted windows while also generating electricity. Although conventional windows typically offer 80% to 90% light transmittance, a 30% transmittance level is sufficient to meet basic indoor lighting needs while delivering substantial power generation. The lightweight and flexible nature of this technology also expands its applications to curved glass surfaces, vehicle windows, and even space-based solar energy systems.
Industry Collaboration Accelerates Commercialization
Alongside these technological breakthroughs, U.S. startup Sofab Inks, based in Kentucky, has made significant strides in commercialization. On July 21, 2026, the company announced the completion of a $6 million seed funding round led by Cloudberry Ventures. Sofab Inks developed Tinfab, a tin-oxide formulation that replaces the commonly used C60 fullerene in perovskite solar cells. C60 fullerene, due to its mechanical fragility, often causes module cracking and voltage loss, whereas Tinfab’s metal-oxide nanoparticles bond six to ten times more strongly than C60, significantly enhancing cell durability.