Solution-Processed Perovskite/Perovskite Heterostructure Via a Grafting-Assisted Transfer Technique

The outstanding properties of perovskites have attracted huge attention in optoelectronic applications. However, the current study mainly focuses on small-area single-layer perovskite films. Surface modification of the polydimethylsiloxane (PDMS) surface has the potential for successful transfer of perovskite thin films and also for forming perovskite/perovskite heterostructures. Nevertheless, current PDMS surface modification processes suffer from fast hydrophobicity gain, thus greatly inhibiting their use in printing perovskite films. In this study, grafting-assisted modification of PDMS was done and long-term hydrophilic PDMS stamps were achieved, making them effective for use in printing perovskite thin films. Highly crystalline MAPbI 3 and MAPbBrI 2 perovskite films were successfully printed with good surface coverage, and the corresponding solar cell devices exhibited outstanding power conversion efficiencies of approximately 14 and 7%, respectively. This grafting-assisted PDMS printing technique also overcame the problem of dissolution in forming stacked perovskite/perovskite heterostructures by solution processibility. As a proof of concept, a cascaded MAPbBrI 2 /MAPbI 3 heterostructure was prepared by transferring an MAPbI 3 layer on top of an MAPbBrI 2 layer. Thus, grafting-assisted PDMS emerged as a promising technique for fabricating stacked perovskite films, opening up avenues for fabricating large-area solution-processable perovskite/perovskite heterostructures for various fields of optoelectronics.