Multimodal host-guest complexation for efficient and stable perovskite photovoltaics.

Zhang, Hong; Eickemeyer, Felix Thomas; Zhou, Zhiwen; Mladenović, Marko; Jahanbakhshi, Farzaneh; Merten, Lena; Hinderhofer, Alexander; Hope, Michael A et al. · Nat Commun · 2021

basic_science · Level V

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Abstract

Formamidinium lead iodide perovskites are promising light-harvesting materials, yet stabilizing them under operating conditions without compromising optimal optoelectronic properties remains challenging. We report a multimodal host-guest complexation strategy to overcome this challenge using a crown ether, dibenzo-21-crown-7, which acts as a vehicle that assembles at the interface and delivers Cs<sup>+</sup> ions into the interior while modulating the material. This provides a local gradient of doping at the nanoscale that assists in photoinduced charge separation while passivating surface and bulk defects, stabilizing the perovskite phase through a synergistic effect of the host, guest, and host-guest complex. The resulting solar cells show power conversion efficiencies exceeding 24% and enhanced operational stability, maintaining over 95% of their performance without encapsulation for 500 h under continuous operation. Moreover, the host contributes to binding lead ions, reducing their environmental impact. This supramolecular strategy illustrates the broad implications of host-guest chemistry in photovoltaics.