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Mohammad Mahdi Tavakoli1

1, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States

Non-radiative recombination loss specially at the interfaces is a big challenge in the perovskite solar cells (PSCs) and affect the performance, stability, reproducibility of devices. Engineering the interfacial regions of the PSCs using an interface layer or additives is an effective strategy to address this issue. Our new findings report on a major breakthrough in the PSCs research. We discovered amazingly effective ways to mitigate the radiationless recombination of charge carriers at the interfaces of the perovskite with either electron transporting layer (ETL) or the hole transporting layer (HTL). In terms of ETL modification, we treat the surface of ETLs in the PSCs using SnO2 and graphene, results in drastically improved the charge transfer properties, retarded the recombination rate and reduced the unwanted interfacial reactions at the interfaces with perovskite film. Moreover, we found that incorporation of the molecular modulators such as adamantanes either at the interface of perovskite with HTL or into the HTL solution prevents non-radiative recombination drastically, resulting in a highly efficient and stable PSC. Based on these techniques, we achieved PSCs (for both planar and mesoporous structures) with electric to power conversion efficiency (PCE) of ~22%, an open circuit voltage of up to 1245 mV, external electroluminescence yield of 2.5% and a great operational stability, which are the records for triple A-cation PSCs with respect to the band gap (1.61 eV). Our proposed approaches open up a promising route for fabrication of cost-effective solar cell and pave the way for the development and commercialization of the PSCs.

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