MAPbI3/agarose photoactive composite for highly stable unencapsulated perovskite solar cells in humid environment

Perovskite solar cells, bearing the merits of facile preparation and remarkable efficiency, has great potential for bringing the photovoltaic industry to a new generation. The photovoltaic market demands high-efficiency, high stability and low-cost fabrication of perovksite solar cells, especially stability to the humid environment for operation. Here, MAPbI(3)/agarose photoactive material for humid stable unencapsulated devices has been proposed. These solar cells have been operated in ambient humid environment without glove box, exhibiting efficiency up to 14.66% and retain 90% of its PCE after 1392 h and 60% of initial PCE after 1972 h in ambient humid environment (RH>70%) without encapsulation. FTIR and XPS measurements reveal two critical factors for the improved stability. The molecular level interactions between agarose and MAPbI(3) passivates the grain boundaries of pemvskite thus preventing its degradation. Moreover, the formation of Li+-agarose complex at the interface between pemvskite layer and hole conductive layer, effectively prevents the water uptake of MAPbI(3) layer. Both effects of passivation and minimization of hygroscopicity of LiTFSI by agarose lower the decomposition speed of perovskite, which obviously increases the power efficiency and stability of device.