Industrial Waste Residue Converted into Value-Added ZnO for Optoelectronic Applications

The present study shows a simple, fast, and cost-effective way of converting industrial waste into a lightweight optoelectronic device to detect UV radiation. An innovative recycling process of ZnO-rich (>95% ZnO) residues from the brass industry has been investigated through the preparation of ceramic targets to be used in the deposition of ZnO thin films. A comparison between optical, structural, and morphological properties of ZnO thin films deposited using the sputtering technique on glass and polyimide substrates was carried out. The ZnO thin films deposited on polyimide substrates were used as seed layers for ultrafast growth of ZnO nanorod arrays by hydrothermal method assisted by microwave irradiation. Laser-induced graphene electrodes were fabricated on the polyimide substrates prior to the ZnO thin film deposition for UV sensor characterization. The produced UV sensor exhibits a responsivity around 12 μA/W for UV light of 365 nm under 10 V bias. The photoresponse measurements showed a stable UV sensor without significant variations in the sensor's responsivity when tested for long periods of time.