Green synthesis of carbon quantum dots derived from mango-leaves (M−CQDs): M−CQDs/ZnO nanorods heterostructure thin films for efficient self-powered UV photodetector applications

• Published in: Applied surface science 2025-03, Vol.685, Article 162032
• Main Authors: Thyda, Lavanya, Joseph, Joel K., Naresh, Koppula, Dasi, Gynaneshwar, Suneetha, S., Thangavel, Rajalingam, Jayalakshmi, Vallamkondu, Amaladass, Pitchamuthu, Thangaraju, Kuppusamy
• Format: Article
• Language: English
• Subjects: Carbon quantum dots; Organic/inorganic heterostructure; Photoluminescence; Self-powered devices; UV Photodetectors; ZnO nanorods
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2024.162032

The schematic representation of M−CQDs/ZnO NRs heterostructure based Self-Powered UV Photodetector photoresponse. [Display omitted] •M−CQDs acts as scattering centre & decreases transmittance slightly.•It shows adsorption of M−CQDs (chemical interaction) onto ZnO NRs.•It ascertains efficient energy transfer from M−CQD to ZnO NRs.•Rλ(81.2 mA/W) & EQE(27.6 %) at 1 V are12 times higher than ZnONRs-device.•M−CQDs/ZnO NRs heterostructure shows 0.5nA at 0 V (1 mW/cm2). The M−CQDs/ZnO nanorods (NRs) heterostructure thin films- based UV Photodetector devices exhibit the photoresponse at zero-bias (0 V) under the ultraviolet light of 365 nm (1, 3 and 5 mW/cm2). The band-edge PL emission (381 nm) intensity of M−CQDs/ZnO NRs heterostructure films is decreasing as compared with ZnO seed layer film, ascribed to the reduced charge recombination which results in the increased photocurrent. The XPS studies ascertain the presence of chemically adsorbed M−CQDs (chemisorption) on ZnO NRs by shifting of peaks to the higher binding energy side. The UV photodetector using M−CQDs/ZnO NRs heterostructure exhibits the higher photocurrent density of 123.49 μA/cm2 with photoresponsivity of 81.2 mA/W and external quantum efficiency of 27.6 % at the bias of 1 V under 1 mW/cm2, as compared with ZnO NRs (93.5 μA/cm2) and seed layer ZnO devices (1.17 μA/cm2). It also exhibited the improved photoresponse (-0.5 nA) at 0 V, which is 1.5 times higher than that (-0.33 nA) of ZnO NRs based device under 1 mW/cm2, showing its application in self-powered devices.