ZnO Quantum Dot/MXene Nanoflake Hybrids for Ultraviolet Photodetectors

Abstract

Efficacious utility of fugacious photons within a limited dimension of photoactive semiconductor thin films provides a facile approach to break through the obstacle for the sensitivity improvement of photodetection. Herein, we demonstrate a facile way to fabricate ZnO quantum dot (QD)/MXene nanoflake photodetectors by uniformly blending various ratios of two-dimensional (2D) Ti 3 C 2 T x nanoflakes into ZnO QD thin films, which can establish a carrier transportation highway and light confinement centers within the photoactive layers. The light absorption of hybrid thin films is obviously enhanced because of the localized surface plasmon resonance effect of MXene nanoflakes, resulting in an expressively enhanced external quantum efficiency by 35 times for the device with 0.1 mg/mL 2D Ti 3 C 2 T x nanoflakes (150.0%) in comparison with that of the pristine photodetector (4.3%). Under 350 nm light illumination (1.72 mW cm −2 ), the carrier transportation in ZnO thin films is significantly accelerated with the hot electron injection from the high-conductivity 2D Ti 3 C 2 T x nanoflakes and thereby the optimal responsivity of 425 mA/ W with an improved response speed at 10 V. Furthermore, ZnO QD/MXene nanoflake photodetectors also exhibit an excellent long-term stability. This work provides an efficient method to fabricate high-performance ZnO UV photoelectric devices in the military and civilian fields at low light intensities.

High Responsivity and EQE of Single ZnO:Sb Microwire/Ti3C2Tx Heterojunction UV Photodetector

“…The photocurrent gradually increases with the UV-light density increasing. The relationship between the photocurrent and the light intensity can be fitted by a power law: , I = K P θ where K is the fitting constant, and θ represents the dependence of I on P . For photoconductive photodetectors, θ is typically between 0.5 and 1.…”

“…The photocurrent gradually increases with the UV-light density increasing. The relationship between the photocurrent and the light intensity can be fitted by a power law: 32,36…”

Emerging applications of MXenes for photodetection: Recent advances and future challenges

“…Owing to the abundant terminations, MXene can be integrated with various active materials giving resultant composites that are promising materials for high-performance photodetectors. Combinations of MXenes with traditional photoresponsive materials, such as transition metal oxides, have been widely investigated and proved to further improve their performance [120,121,123,133]. For instance, Guo et al demonstrated that the deep ultraviolet (DUV) photovoltaic performance of the Zn 2 -GeO 4 crystal could be greatly enhanced by addition of 2D MXene flakes [120].…”

“…The enhanced photoresponse performance are mainly due to the synergistic effect of Ti 3 C 2 and Zn 2 GeO 4 nanowires, where the conductive MXene promotes the carrier transport and the large contact interfaces accelerate the separation of electron-hole pairs. Li et al established an efficient carrier transportation channel by blending 0D ZnO QDs and 2D Ti 3 C 2 T x nanoflakes, which confines the light within the photoactive layers and enhances the sensitivity of photodetection [123]. Owing to the localized surface plasmon resonance effect of the MXene, the light absorption of ZnO/Ti 3 C 2 T x film is enhanced and an impressively improved EQE (150%) was achieved.…”

Ultraviolet Photodetector Based on Poly(3,4-Ethylenedioxyselenophene)/ZnO Core–Shell Nanorods p-n Heterojunction

“…Recently, ultraviolet photodetectors (UV PDs) has been widely used in the following fields, including ultraviolet guidance, fire detection, optical communications and medical applications [ 1 – 4 ]. Among the wide-bandgap semiconductors materials, ZnO is one of the best candidate materials for UV PDs due to its unique performance, such as wide direct bandgap (~ 3.3 eV) and high exciton binding energy (60 meV) [ 5 , 6 ], with excellent photoelectric conversion characteristics, thermal stability, nontoxic, easy preparation and inexpensive [ 1 , 7 , 8 ]. However, ZnO-based UV PDs still have the problems that weak light response [ 9 ] and response time longer [ 10 ], which limits its application in UV PDs [ 11 ].…”