UV detector based on an FTO/TiO₂/MoO₃ heterojunction with a potential well trapping electrons in the dark

Abstract

An FTO/TiO 2 /MoO 3 based UV detector has been fabricated through the synthesis of TiO 2 nanowires (NWs) on FTO using the hydrothermal method, the preparation of MoO 3 on TiO 2 NWs by the spin-coating method, after the hydrothermal synthesis, and the preparation of Ag electrodes on the FTO and MoO 3 . The detector exhibits an excellent performance of photo-todark current ratio of more than two orders of magnitude. This performance is produced because the dark current under 2.2 V bias has been significantly inhibited due to the electronic potential well formed by the energy band distribution while the photocurrent has increased in comparison with FTO/TiO 2 based detectors under the same conditions which also have a higher photo-todark current ratio without the MoO 3 content. Not only does this study take advantage of 1D NWs and 2D nanostructures, but it also provides a new way to inhibit the dark current of detectors.

Solution processed transparent anatase TiO2 nanoparticles/MoO3 nanostructures heterojunction: high performance self-powered UV detector for low-power and low-light applications

“…† The reverse current started increasing slightly at À0.4 V, but the corresponding forward current was one order of magnitude higher which is comparable to the earlier observations with other heterojunction devices. 40,54,55 The ideality factor which was greater than unity (2.98) indicates that the charge transport mechanism deviated from the thermionic emission theory applicable for an ideal diode. To further investigate the charge transport mechanism, power-law compliance was considered and the forward I-V data were plotted in a log I-log V scale 56 (Fig.…”

“…A recent report on a TiO 2 /MoO 3 UV detector employed hydrothermally synthesised 1D TiO 2 (rutile) nanowires with MoO 3 nanostructures, and used a bias voltage of 2.2 V, with no observation of self-powered performance. 40 According to the literature, 1D TiO 2 nanostructures have been extensively used in TiO 2 based UV detectors as well as in TiO 2 /MoO 3 based devices for various other energy harvesting applications. [21][22][23][24] Although 1D TiO 2 nanostructures offer high specic area, dened geometry and efficient unidirectional carrier transport, the high surface recombination due to their high surface to volume ratio is considered as one of the potential limiting factors for their use in energy harvesting systems.…”

“…42 Thus, the TiO 2 /MoO 3 bilayer heterojunction using TiO 2 nanoparticles would not have this limitation and also would be more transparent, unlike the one reported based on hydrothermally grown TiO 2 nanowires. 40,43 As already mentioned, transparent devices are considered as the major players in future energy saving technology due to their unique optical and electrical properties. It's also notable that previous reports did not explore TiO 2 with anatase crystal structure, for which the electron mobility is known to be relatively higher.…”

Organic Ternary Bulk Heterojunction Broadband Photodetectors Based on Nonfullerene Acceptors with a Spectral Response Range from 200 to 1050 nm

“…A photodetector (PD) is a device that can convert optical signals into electrical signals and has a wide range of applications in remote sensing, imaging, and industrial automatic control systems. − Organic/inorganic photodetectors (OPDs) have the advantages of low cost, lightweight, flexibility, and uncomplicated processing, thus showing great application potential in new fields such as electronic skin, virtual reality, and wearable devices in recent years. − In particular, broadband OPDs have been successfully used in significant fields such as astronomical detection, remote sensing, and infrared imaging. Generally, OPDs employ the bulk heterojunction (BHJ) as the active layer composed of a polymer donor and a fullerene acceptor to promote charge separation and photon absorption. , Effective exciton dissociation and a broad absorption spectrum are the prerequisites for achieving high responsivity in OPDs.…”

“…In this work, a novel low-band-gap NFA sodium indocyanine green (Ir-125) is introduced, mixed with a fullerene derivative acceptor [6,6]-phenyl C61-butyric acid methyl ester (PC61BM) and a conjugate polymer donor poly(3-hexylthiophene) (P3HT), to form a ternary BHJ-active layer, forming a high-performance BHJ OPD with ultrawide spectral response from the UV (200 nm) to visible light to NIR (1050 nm) region. It exhibits complementary absorption and relatively high external quantum efficiency (EQE) and mixed with the pure phase on the scale of exciton diffusion length.…”