Dual-functional quantum-dots light emitting diodes based on solution processable vanadium oxide hole injection layer

Abstract

Dual-functional quantum-dots light emitting diodes (QLEDs) have been fabricated using solution processable vanadium oxide (V2O5) hole injection layer to control the carrier transport behavior. The device shows selectable functionalities of photo-detecting and light-emitting behaviors according to the different operating voltage conditions. The device emitted a bright green light at the wavelength of 536 nm, and with the maximum luminance of 31,668 cd/m2 in a forward bias of 8.6 V. Meanwhile, the device could operate as a photodetector in a reverse bias condition. The device was perfectly turned off in a reverse bias, while an increase of photocurrent was observed during the illumination of 520 nm wavelength light on the device. The interfacial electronic structure of the device prepared with different concentration V2O5 solution was measured in detail using x-ray and ultraviolet photoelectron spectroscopy. Both the highest occupied molecular orbital and the gap state levels were moved closer to the Fermi level, according to increase the concentration of V2O5 solution. The change of gap state position enables to fabricate a dual-functional QLEDs. Therefore, the device could operate both as a photodetector and as a light-emitting diode with different applied bias. The result suggests that QLEDs can be used as a photosensor and as a light-emitting diode for the future display industry.

Facile Synthesis of Two Dimensional (2D) V2O5 Nanosheets Film towards Photodetectors

“…Figure 3 c presents the O 1s core level XPS spectrum, and the peaks at 532.17 eV and 530.28 eV belong to adsorbed oxygen and lattice oxygen, respectively [ 57 ]. Our XPS spectrum matches well with those of the V 2 O 5 nanosheets reported in the literature [ 33 , 56 , 57 ]. Meanwhile, the Raman technique is a powerful method to identify the chemical composition of the material.…”

“…Meanwhile, the spectra of the V 2p 1/2 oxidation state were separated to V 4+ (523.69 eV) and V 5+ (525.07 eV) [ 55 ]. The V 5+ state at the high-binding energy corresponds to V 2 O 5 , while the V 4+ state responds to VO 2 , which indicates the gap state [ 56 ]. Figure 3 c presents the O 1s core level XPS spectrum, and the peaks at 532.17 eV and 530.28 eV belong to adsorbed oxygen and lattice oxygen, respectively [ 57 ].…”

High-Resolution Colloidal Quantum Dot Film Photolithography via Atomic Layer Deposition of ZnO

“…Semiconductor nanocrystals or colloidal quantum dots (QDs) are one of the potential emissive display materials owing to their excellent optoelectronic properties, such as large-scale synthesis and high color purity. − QD-based light-emitting devices have been used for information display, − solid-state lighting, , and multifunctional photodetectors. , The device performance and lifetime of QD light-emitting diodes (LEDs) have significantly increased to theoretical limits for all primary colors, i.e., red/green/blue (RGB). ,− Recently, environmentally friendly QDs have been successfully synthesized with high photoluminescence (PL) quantum yield (QY), and a high-performance electroluminescence (EL) device was successfully fabricated . QDs can be simply made into film, and charge transport layers (CTLs) can be incorporated between two electrodes to generate light by electrical excitation in QD electroluminescence (EL) devices. , Wet chemistry-based synthesis is beneficial for large-scale processes and ink preparation for printing, but the process also limits the high-resolution displays for practical applications.…”

“…1−3 QD-based light-emitting devices have been used for information display, 4−7 solid-state lighting, 8,9 and multifunctional photodetectors. 10,11 The device performance and lifetime of QD light-emitting diodes (LEDs) have significantly increased to theoretical limits for all primary colors, i.e., red/green/blue (RGB). 7,12−14 Recently, environmentally friendly QDs have been successfully synthesized with high photoluminescence (PL) quantum yield (QY), and a high-performance electroluminescence (EL) device was successfully fabricated.…”

Vertically Aligned Porous VxOy Nanofilms with Pt Decoration for Sub-ppm H2 Gas Sensors

“…The V 5+ state at the higher binding energy corresponds to V 2 O 5 , while the V 4+ state resembles VO 2 , suggesting the entire oxidation state of V x O y , that is, V 2 O 5 with VO 2 inclusions. In the spectra of O 1s (Figure d), the asymmetric O1s peak could be deconvoluted into three fitted peaks V 5+ (530.05 eV), V 4+ (531.05 eV), and chemisorbed PtO or Pt­(OH) 2 (532.12 eV). ,, According to Li et al, the binding energy peak at ∼532.17 eV in the O 1s core-level spectrum is attributed to adsorbed oxygen ions (O 2ads – , O ads – , or O ads 2– ) on the surface of the material. These oxygen ions can interact with target gases, enhancing the material gas-sensing properties.…”