Thin-film solution-processed solar cells based on a hybrid organohalide lead perovskite semiconductor have achieved certified power conversion efficiencies (PCEs) exceeding 22%. Early efforts to bring this technology from the lab to the market quickly revealed certain disadvantages of perovskites, including the use of toxic lead, the diffusion of ionic defects causing a hysteresis effect, long-term stability, water sensitivity, the complexity of the ink formulation, as well as the cost efficiency and compatibility of the interface materials. Of these, a critical limitation on commercializing this technology is the absence of suitable hole-transporting materials (HTMs) that offer full performance without sacrificing long-term stability, and with low material costs and printability from green solvents.
In this work1, we present a generic interface architecture that combines solution-processed, reliable, and cost-efficient hole-transporting materials, without compromising efficiency, stability or scalability of perovskite solar cells. Tantalum doped tungsten oxide (Ta-WOx)/conjugated polymer multilayers offer a surprisingly small interface barrier and form quasi-ohmic contacts universally with various scalable conjugated polymers. Using a simple regular planar architecture device, Ta-WOx doped interface-based perovskite solar cells achieve maximum efficiencies of 21.2% and combined with over 1000 hours of light stability based on a self-assembled monolayer. By eliminating additional ionic dopants, these findings open up the whole class of organics as scalable hole-transporting materials for perovskite solar cells.
1. Yi Hou. et al. A generic interface to reduce the efficiency-stability-cost gap of perovskite solar cells. Science, In press.