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 uncoordinated Pb²⁺ and I^- ions to form a moisture-proof and heat-dissipating layer anchored onto both top and side surfaces of the perovskite film. The hydrophobicity of the MAPbI₃ film treated by Eu(OA)₃ remarkably increases, as demonstrated by the enhancement of the 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 the 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 conditions 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 nonradiative recombination.