In this study, the authors fabricated high performance core–shell nanostructured flexible photodetectors on a polyimide substrate of Kapton. For this purpose, p-type copper indium gallium selenide (CIGS) nanorod arrays (core) were coated with aluminum doped zinc oxide (AZO) films (shell) at relatively high Ar gas pressures. CIGS nanorods were prepared by glancing angle deposition (GLAD) technique using radio frequency (RF) magnetron sputtering unit at room temperature. AZO films were deposited by RF sputtering at Ar pressures of 1.0×10−2 mbar (high pressure sputtering) for the shell and at 3.0×10−3 mbar (low pressure sputtering) to create a top contact. As a comparison, the authors also fabricated conventional planar thin film devices incorporating CIGS film of similar material loading to that of CIGS nanorods. The morphological characterization was carried out by field-emission scanning electron microscope. The photocurrent measurement was conducted under 1.5 AM sun at zero electrical biasing, where CIGS devices were observed to absorb in the ultraviolet-visible-near infrared spectrum. GLAD core–shell nanorod photodetectors were shown to demonstrate enhanced photoresponse with an average photocurrent density values of 4.4, 3.2, 2.5, 3.0, and 2.5 μA/cm2 for bending angles of 0°, 20°, 40°, 60°, and 80°, respectively. These results are significantly higher than the photocurrent of most of the flexible photodetectors reported in the literature. Moreover, our nanorod devices recovered their photoresponse after several bending experiments that indicate their enhanced mechanical durability. On the other hand, thin film devices did not show any notable photoresponse. Improved photocurrent of CIGS nanorod devices is believed to be due to their enhanced light trapping property and the reduced interelectrode distance because of the core–shell structure, which allows the efficient capture of the photo-generated carriers. In addition, enhanced mechanical durability is achieved by the GLAD nanorod microstructure on a flexible substrate. This approach can open a new strategy to boost the performance of flexible photodetectors and wearable electronics.

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In this work, we report the fabrication and characterization of copper(II) oxide (CuO) nanoleaf structures (NS) grown on Cu sheets by a facile hot-water treatment (HWT) method without using catalyst materials. In addition, simple photoconductive devices based on asprepared CuO nanoleaves were fabricated to study the optical and photocurrent response of CuO NSs. Scanning electron microscopy images revealed the formation of uniform and dense nanoleaves morphology of CuO on Cu sheets. X-ray diffractometer patterns indicated that synthesized nanostructures have a monoclinic CuO structure. Furthermore, X-ray photoelectron spectroscopy results demonstrate the formation of the Cu−O chemical bond which confirmed the formation of the CuO phase. For the fabrication of the photoconductive devices, the CuO/Cu samples were coated with an aluminum-doped ZnO (AZO) shell by sputter deposition at room temperature. CuO NSs show high-broadband ultraviolet/visible spectroscopy (UV/vis) absorbance with marked enhancement after AZO coating. Current density−voltage (J−V) measurements show that AZO/CuO/Cu devices exhibit a photocurrent density response of 9.65 ± 0.43 μA/cm 2 with a rise time of 0.195 s and decay time of 0.192 s. They also indicate a Schottky contact between p-type CuO NSs and the Cu substrate. Photocurrent increases and rise time and decay time decrease with an applied forward bias (e.g. ∼19.00 μA/cm 2 at 1.0 V with a rise time of ∼0.100 s and decay time of 0.096 s). Optical band gap of CuO NSs was calculated to be 1.44 ± 0.13 eV, by the analysis of Tauc's plot. These results indicate that our photoconductive devices based on CuO NSs prepared by HWT can achieve high light absorption and good photocurrent response for optoelectronic applications.