Improving Moisture Proof and Heat Dissipation of Perovskite Solar Cells with Metal Oleate Passivation Layer

Europium oleate (Eu(OA)₃) is designed as a multifunctional passivation layer coated onto methylammonium lead iodide (MAPbI₃) films to delay the degradation of perovskite solar cells (PSCs) caused by moisture and heat. The carbonyl group and Eu³⁺ ions of Eu(OA)₃ subsequently coordinate with the uncoordinated Pb²⁺ and I¯ ions to form a moisture‐proof and heat‐dissipating layer anchored onto both top and side surface of perovskite film. The hydrophobicity of MAPbI₃ film treated by Eu(OA)₃ remarkably increases as demonstrated by the enhancement of average contact angle from 54.9 ° to 90.5 °. Besides, the thermal conductivity of PSCs incorporated with Eu(OA)₃ is 1.3 times that of control device, resulting in a 1.34 °C reduction on surface temperature at 85 °C. The optimized PSCs demonstrate a T₈₀ lifetime of 1056 h (only 180 h for pristine PSCs) at condition of room temperature and relative humidity (RH) of 40 %. Moreover, the T₈₀ lifetime for optimized PSCs is four times that of the control device at 85 °C and RH of 85 %. Finally, the power conversion efficiency (PCE) of PSCs treated with Eu(OA)₃ increases from 17.36 % to 18.99 %, attributed to the effective defect passivation and suppression of non‐radiative recombination.