Highly stable semi-transparent CH₃NH₃PbI₃ sandwich type perovskite solar sub-module with neutral color

∼10% semi-transparent neutral color sandwich type CH₃NH₃PbI₃ (MAPbI₃) perovskite sub-module (active area = 25 cm²) with UV cross-linked polystyrene passivation layer showed ∼2.8% degradation of initial efficiency after continuous light soaking of 1 Sun for 1000 h at 55 °C. Due to the role of island-morphology-MAPbI₃ as selective UV-cut mask, the UV curable monomeric compounds on the island-morphology-MAPbI₃/blocking TiO₂/F-doped tin oxide substrate could be selectively cross-linked polymerized by exposure of UV light and consequently the UV cured passivation layer could be reproducibly deposited in the gaps between perovskite islands after simple washing of unreacted residue. The degree of cross-linking was controlled by adjusting the concentration of divinylbezene cross-linker in the UV curable monomeric compounds from 1 to 7 mol% and eventually 5 mol% sample showed the best power conversion efficiency of 11.58% for forward scan condition and 11.95% for reverse scan condition (active area = 1 cm², geometric fill factor = 100%, average = 10.28 ± 0.96% for 40 samples: average visible transmittance = 20.1%). When the active area of the MAPbI₃ perovskite sub-module increases to 1 → 25 → 100 cm², the power conversion efficiency was slightly decreased to 11.95 → 10.16 → 7.08% at 1 Sun condition.