Contact Engineering of Inkjet-printed Organometallic Halide Perovskites for Photodetectors and Solar Cells

Inkjet printing is an emerging approach that holds great potential to revolutionize the fabrication of electronic and optoelectronic devices since it provides a cost-effective, time-efficient, and more flexible route for device fabrication. In this work, we fabricated all inkjet-printed heterostructure photodetectors (PDs) on a flexible polyimide (PI) substrates with engineered solution-processed electrical contacts. The engineered silver (Ag) and graphene (Gr) inks were directly inkjet-printed on the solution-processed two-dimensional (2D) organometallic halide (CH 3 (CH 2 ) 3 NH 3 ) 2 (CH 3 NH 3 ) n-1 Pb n I 3n+1 (n = 4) layered perovskites, where we demonstrate their utility as efficient electrical contacts to 2D perovskites. We will report on the device figures of merit measured in such devices, both for the Ag-perovskite and Gr-perovskite interfaces. These values will be also compared with prior reported evaporated metal contacts made to 2D perovskites PDs, though such reports are very limited. The thermionic emission model is invoked to determine the Schottky barrier (ΦB) through the temperature-dependent transport measurements we will present for the two contact electrodes. This work also provides the basis for utilizing the 2D perovskites in solar cell structures by sandwiching the same perovskite layer between the TiO2 and Spiro-MeOTAD electron-transfer layer (ETL) and hole-transport layer (HTL), respectively. Also, the engineered Ag and Gr ink has the potential to be used as an electrode in inkjet printed flexible perovskite solar cells (PSCs).