Year: 2025

The Cover Art in the ACS Applied Electronic Materials

Recently, the Supplementary Cover Art for manuscript: “Graphene-ZnO Thin-Film Heterostructure-Based Efficient  UV Photosensors” has been published in the ACS Applied Electronic Materials. Dr Ravi K. Biroju, who is the main author of this article explains, that this work basically demonstrates fabrication of CVD grown graphene/ZnO thin-film van der Waals heterostructures. When we combine a wide direct band gap semiconductor such as ZnO and a highly conductive layer of graphene, we get a unique platform for applications such as photosensors and gas sensors. Under light illumination, the effective separation of photo-generated electron−hole pairs by the local electric field suppresses carrier recombination rates and increases carrier lifetime. This leads to an increased free carrier density. It can reduce the Schottky barrier between graphene and the ZnO thin film, facilitating the transport and collection of photocarriers. As a result, a high Ilight/Idark ratio can be achieved, much higher than for bare ZnO thin films or ZnO nanostructures.

Graphene-ZnO Thin-Film Heterostructure-Based Efficient UV Photosensors

Graphene-ZnO Thin-Film Heterostructure-Based Efficient UV Photosensors

Ravi K. Biroju*, Sanat Nalini Paltasingh, Mihir Ranjan Sahoo, Soumen Dhara, Dipak Maity, Viliam Vretenár, P. K. Giri, Tharangattu N. Narayanan, Saroj Kumar Nayak

In: ACS Appl. Electron. Mater. 2025

https://doi.org/10.1021/acsaelm.5c00348

Abstract

Graphene-based ZnO thin-film hybrids (GR-ZnO) have shown interesting properties for electronic and optoelectronic applications, such as enhanced UV photodetection and photocatalysis. The interaction and explicit role of large-area single-layer chemical vapor deposition (CVD)-grown graphene in the improved photophysical properties in such a kind of GR-ZnO hybrids have not been well-understood in recent reports. In the present work, we fabricated a photosensor made with large-area monolayer CVD GR-ZnO thin-film hybrids, which showed improved UV photodetection with high values of UV sensitivity and responsivity compared to bare ZnO films. The GR-ZnO thin-film hybrid photosensors demonstrated about a 20 time improvement in photoresponsivity (9.87 × 103 A/W) compared to the bare ZnO thin film (4.93 × 102 A/W). We investigated the origin of the high photosensitivity of GR-ZnO, and it is explained based on a comparatively large absorption coefficient, enhancement of the number of photogenerated carriers, and a reduction of the recombination rates of these carriers based on density functional theory (DFT) calculations. The high mobility of the graphene layer provides an efficient and faster charge transfer pathway for photogenerated carriers at the interface between ZnO and the graphene layers.