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 MAPbI3 and MAPbBrI2 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 MAPbBrI2/MAPbI3 heterostructure was prepared by transferring an MAPbI3 layer on top of an MAPbBrI2 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.