Thin-film solar cells based on hybrid organo-halide lead perovskites achieved power conversion efficiency exceeding 22% and are already on par with the well-established thin film photovoltaic technologies. One major bottleneck allowing to drive this technology further towards commercialization are the interfacial losses at the hole transporting materials, leaving few material choices and inevitably compromise device efficiency or stability. Developing a novel concept for solution processed, reliable, cost efficient and improved hole transporting materials which do not compromise efficiency, stability and scalability,1,2) becoming of paramount importance and still challenging the perovskite community.
Here, we present for the first time a novel interface concept, which combines solution-processed, reliable, and cost-efficient hole-transporting materials, without compromising efficiency, stability or scalability of perovskite solar cells. This multilayer interface offers a surprisingly small interface barrier and forms ohmic contacts universally with various scalable conjugated polymers. Time of flight secondary ion mass spectrometry (ToF-SIMS) further reveal that this interface is acting as a protective layer against the diffusion of Au into the p-type polymer. The absence of interface shunts is further suggested to enhance the stability of the corresponding perovskite devices. Using a simple regular planar architecture device, perovskite solar cells achieve maximum efficiencies of 19.0% combined with over 1000 hour of light stability, which is the highest performance so far for regular architecture perovskite solar cells using dopants-free HTMs. These findings open up the whole class of π-conjugated polymers, oligomers, and molecules as low-cost and scalable hole-transporting materials for perovskite optoelectronics without the need for additional ionic dopants.
We believe that these findings open the whole class of π-conjugated polymers, oligomers and molecules as low-cost and scalable hole-transporting materials for perovskite optoelectronics without the necessity of additional ionic dopants. The universal strategy developed in this work will effectively maximum the performances of all the previous developed and broadly stimulate the material community to further design novel HTMs to follow the rules with optimum energetic levels.
1) Y. Hou, COR. Quiroz, et al. Adv. Energy Mater. , 7, 1501056 (2015)
2) Y. Hou, W. Chen, et al. Adv. Mater., 28, 5112-5120 (2016).