Sunscreen-Inspired ZnO/PEG Composites for Flexible Ultraviolet Photodetectors with a Giant On–Off Ratio

Abstract

Zinc oxide (ZnO) nanomaterials have attracted much attention in UV photodetectors owing to the suitable band gap and high photoelectric conversion efficiency. However, the loose structure of nanomaterials assembled by a low-temperature process cannot meet the mechanical requirements of flexible photodetectors. The high dark current caused by defects in ZnO severely drags down the response performance of photodetectors. To address these issues, we have proposed a novel strategy for constructing flexible photodetectors based on ZnO and poly(ethylene glycol) (PEG) composites. Inspired by the sunscreen, the addition of PEG can enhance the interaction of ZnO nanoparticles, thus improving the film-forming ability and the mechanical endurance of the composites. By coating the ZnO/PEG composite on a common printing paper, the flexible photodetector shows unexpected good performance, such as a high responsivity of 1.77 A·W–1 and a large specific detectivity of 3.89 × 1013 Jones. Notably, a giant on–off ratio of up to 1.99 × 105 has been achieved by suppression of dark current. The device also exhibits satisfactory mechanical flexibility after long-term bending tests. In addition, the low-cost raw materials and scalable manufacturing processes further expand its application prospects in flexible optoelectronic technologies.

Recent Advances in Solution-Processed Zinc Oxide Thin Films for Ultraviolet Photodetectors

“…The inclusion of poly­(ethylene glycol) (PEG), which was inspired by sunscreen, improved the interaction of ZnO nanoparticles and increased the composites’ capacity to form films and their mechanical toughness. A flexible PD created by coating standard printer paper with the ZnO/PEG combination exhibits a considerable reduction in the dark current, which results in a high responsivity of 1.77 A/W and a large specific detectivity of 3.89 × 10 13 Jones . Graphene QD-decorated ZnO (ZnO:GQD) studied by Tran et al showed less surface roughness, reduced nanoparticle size, higher photogenerated carrier transport, and extended carrier lifetime.…”

Flexible and Stretchable Light-Emitting Diodes and Photodetectors for Human-Centric Optoelectronics

“…The facile fabrication methods from soluble, low-temperature processable properties of the NPs also improve the device’s flexibility and stretchability. Thus, the NPs integrated with flexible substrates enable the implementation of the flexible/stretchable PDs based on ZnO NPs, − Ag NPs, PbS QDs, − CdSe QDs, Ag 2 Se NPs, and PbSe QDs, HgTe QDs . This section will present 0D nanomaterial-based inorganic, flexible/stretchable PDs.…”

Performance optimization of self-powered ultraviolet and short-wavelength blue photodetectors based on ZnO/SrTiO3 heterojunctions by annealing treatment

“…ZnO is recognized as a wide bandgap semiconductor, featuring a bandgap of 3.3 eV, notable for its high carrier mobility and significant ultraviolet (UV) absorption coefficient, making it extensively employed in UV PDs. 26,27 It is also important to highlight that the electron affinity of ZnO is 4.2 eV, presenting a minor band shift relative to SrTiO 3 , which has an electron affinity of 4.0 eV. 28 Consequently, ZnO serves as an optimal partner for fabricating SrTiO 3 heterojunctions.…”