Thickness dependent photodetection properties of solution-processed CuI films: Towards cost-effective flexible visible photodetectors

Abstract

Herein, solution-processed earth-abundant CuI films are employed for low-cost visible photodetectors on either rigid Si/SiO2 (100 nm) wafers or flexible polyimide (PI) substrates. The CuI film thickness dependent structure, morphology and optical properties are investigated via film analysis methods including X-ray spectroscopy (XPS), elucidating that consistent shift for binding energy position of constituent elements and variation in the elemental composition are highly relevant with photo detective properties (PPs). Among various film thickness, the highest PPs for photodetectors on the Si/SiO2 substrate is obtained for 500 nm condition in the respective of (i) photosensitivity (403.26 ± 20.86%), (ii) photoresponsivity ((65.16 ± 3.35) mA/W), and (iii) specific detectivity ((1.66 ± 0.45) × 1010 Jones). Moreover, flexible photodetectors with the optimized condition show 90% level PPs, as compared with the rigid substrate, anticipating that CuI can be a promising material for flexible photodetectors.