Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV19)
Publication date: 6th February 2020
High quality of perovskite solar cells interfaces is mandatory to advance toward a stable and commercially viable technology. Employing inorganic selective contacts is appealing and considered a key requirement for the stability goal [1], however metal oxides - perovskite interface remains a complex object. Metal oxides semiconducting properties are due to their defectivity, with the surface chemistry strongly depending on processing conditions and dramatically affecting surface electronics. When taking into account the dynamic defectivity of perovskite the picture blurs even further.
We focused on NiO/Perovskite interface, in p-i-n PSC with 18% power conversion efficiency. NiO is among the best candidates to replace Spiro-OMeTAD in devices, unfortunately its performances as HSL still lack behind molecular and polymeric alternatives. We moved from NiO bulk to its surface, recognizing the key role of the latter. By employing an ultra-thin, solution processed inorganic interlayer we addressed the hole-electron recombination at the interface, thus enhancing the Voc of the devices, that constitutes a key limit of NiO/PSK interface. More importantly, we identified and characterized the interfacial redox activity. Strategies to overcome this detrimental process are discussed, showing how a superior electrical stability can be achieved, together with better performances.
The robust solutions developed are important per se, but will also inspire future research developments to rationally shape the interfaces, and the performances and stability of perovskite solar cells.