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

Abstract

Zinc oxide (ZnO) is versatile among semiconducting metal oxides with properties such as high photosensitivity, highly tunable specific surface area, nontoxicity, piezoelectricity, almost 85% optical transparency in the visible region, large exciton binding energy, and good biocompatibility. ZnO also shows excellent chemical and thermal stability. This n-type semiconducting material finds several applications in optoelectronic devices such as photodetectors (PDs) due to its wide and direct band gap. Beyond these, the nanostructured ZnO shows unique and tunable properties suitable for flexible and wearable devices. Recently, solution-based deposition techniques have achieved device-quality films at a low cost. This is mainly because the ease of intermixing and controlling the stoichiometry of the precursors is possible with a variety of solution-based synthesis methods, unlike physical deposition methods. This review summarizes the recent developments related to solutionderived ZnO-based thin films for ultraviolet (UV) detector applications. The different strategies used for the fabrication of UV detectors, major improvements achieved with solution-processed ZnO thin films of different morphologies, and their UV photoresponse behavior while in conjugation with other potential materials are discussed in this Review. However, a few shortcomings of the solution-based ZnO thin films, such as low quality and high defect density, remain challenges for the advancement of UV PD application. Thus, this Review concludes with a brief overview of such challenges and an outlook on the emerging research directions toward improving the capabilities of solution-processed ZnO-based UV detectors for various purposes.

Temperature-Dependent Structure–Property Relationship of Mn-Doped Cs2AgInCl6 Thin Films Impacts Its Application as a Self-Powered UV Photodetector

“…The responsivity of the devices is determined using the formula ( I p – I d )/ PA d , where I p represents the photocurrent and I d represents the dark current, P represents the incident photon radiation (14 mW/cm 2 ) and A d is effective device active area. , Here, both pristine and Mn-doped CAIC devices exhibit responsivity values of 0.03 and 0.06 A/W, respectively. The detectivity for these samples are calculated by using the formula , where R is responsivity and e is a charge of the electron, and I d is the dark current. , The obtained detectivity of 1.2 × 10 7 and 4.7 × 10 8 Jones for pristine and Mn-doped CAIC devices, the observed detectivity values are similar to the previous reports, particularly for UV detection. − In comparison to pristine CAIC, Mn-doped CAIC NCs have exhibited excellent performance in UV photodetection, which confirms that after doping with Mn the device performance has been doubled. A further improvement in the optimization of these materials with different hole transport layers may lead to an increase in the figure of merits.…”

Electrophoretic Deposition of Conformal β-Ga2O3 Films on Arbitrary Substrates for Heterojunction-Based Deep-Ultraviolet Photodetectors

“…It is important to notice that the large photodetector device size of 3 cm 2 when compared to others (device size, ∼mm 2 to μm 2 ) is responsible for observed low responsivity and detectivity values (see Table ). Additionally, the performance of the devices is low (as expected) when compared to vacuum-based methods, which typically have better crystalline quality . The optimization of EPD parameters to deposit thinner films, shrinking the device size, use of interdigitated or other novel geometries are to be further explored to achieve high-performance deep-UV photodetectors.…”

Self-Powered Photoelectrochemical Photodetectors Based on a CsPbBr3/S-g-C3N4 Heterojunction-Sensitized 3D ZnO Nanostructured Thin Film

“…Photodetector (PD) devices, which are magnificent tools for the conversion of optoelectronic signals, have been implemented in optical communications, biological imaging, and environmental surveillance . In recent years, PD devices based on metal-oxide semiconductors, especially zinc oxide (ZnO) nanostructures, have been widely used due to their beneficial properties such as ease of manufacturing, morphology and defect control, eco-friendly nature, and excellent stability. , Low-temperature synthesis can provide various morphologies on nano- and microscales, making ZnO a promising material in optoelectronic and photoelectrochemical devices. − Thus, there is a great variety of ZnO-based photoelectrodes and PD devices bearing various nanostructures, such as nanowires (NWs), nanorods (NRs), , nanotubes (NTs), , nanodisks (NDs), nanosheets (NSs), − and nanoflowers (NFs) .…”