Tailored Supramolecular Interface Enables Efficient and Stable Tin Halide Perovskite Photovoltaics

The efficiency and lifetime of tin halide perovskite solar cells (THPSCs) lag far behind those of their lead counterparts, which is mainly attributed to the low-quality of tin perovskite films as a result of their poorly controlled crystallization. Here, we introduce 3D polydentate methyl-β-cyclodextrin (CD) on top of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and such a supramolecular interlayer leads to well-regulated crystallization. The attenuate coordination between CD and ammonium at the supramolecular interface facilitates the nucleation rate, and the multisite interaction in different spatial directions retards their crystal growth, resulting in denser and defect-less tin perovskite films. Moreover, such a supramolecular interlayer not only enables better energy alignment but also weakens the acidity of PEDOT:PSS. As a result, the efficiency of THPSCs with a tailored supramolecular interface is increased to 14.94% with a new record-high VOC of up to 1.017 V, and the unencapsulated devices exhibit an outstanding stability after nearly 4000 h of storage.