High-resolution patterning of organohalide lead perovskite pixels for photodetectors using orthogonal photolithography

摘要

Organohalide lead perovskite (CH3NH_3PbI_3) is a novel material with promising applicability for visible light photo-detectors. The ability to develop perovskite photo-detector devices using a low temperature solution based process allows straightforward combinations with other materials, including traditional crystalline semiconductors, with minimal contributions to cost and process complexity. There is, however, a need for high-resolution structuring of the perovskite film to minimize cross-talk between neighboring detectors (pixels) for imaging purposes. This work presents a method to develop Ch_3NH_3PbI_3 thin films possessing high-resolution patterning, using lithography processing with hydrofluoroether solvents. The results presented herein confirm that, unlike the majority of traditional solvents utilized in conventional photolithography, hydrofluoroethers do not adversely affect CH_3NH_3PbI_3 films, enabling photolithographic processing. Transfer of the resist pattern is achieved using a SF6 plasma functionalization process which extracts iodine and organic components from the film, converting the perovskite into PbF_2. This work also demonstrates that isolation of perovskite photodetecting pixels with a 20 μm-wide stripe of PbF_2 leads to a 4.5-fold reduction in the cross-talk between neighboring pixels. It is believed that our method will facilitate simple monolithic integration of perovskite photodiodes to the silicon backplane chip utilized in active-pixel sensor and charge-coupled device applications.