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, MAPbI3/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 MAPbI3 passivates the grain boundaries of perovskite thus preventing its degradation. Moreover, the formation of Li+-agarose complex at the interface between perovskite layer and hole conductive layer, effectively prevents the water uptake of MAPbI3 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. MAPbI3/agarose photoactive composite serves as the humid stable light absorber for unencapsultated perovskite solar cells in air. Environmental stability for almost 2000 h are achieved. ~46% enhancement in the light-to-electric efficiency are accomplished due to the passivation of agarose on perovskite and that MAPbI3/agarose photoactive composite has potential in improving the operational stability of perovskite solar cells in humid air without glove box. [Display omitted] •MAPbI3/agarose photoactive material is applied as the humid stable light absorber.•Effects of passivation and hygroscopicity minimization of LiTFSI by agarose lower the decomposition speed of perovskite.•The unencapsulated device shows 1392 h stability in ambient humid environment (RH>70%) without glove box.