Flexible Quasi‐2D Perovskite/IGZO Phototransistors for Ultrasensitive and Broadband Photodetection

Abstract

In the past decade, high-performance, low-cost, and robust photodetectors have become one of the key components for a wide range of commercial systems, including environment and security monitoring, [1] wearable electronics, [2] free-space communications, [3] and biomedical diagnostics, [4] etc. As inspired by these applications, various emerging materials, such as quantum dots, [5] carbon nanotubes, [6] graphene, [7] and transition-metal dichalcogenides, [8] are extensively explored for the efficient photodetection. In particular, organic-inorganic hybrid perovskites (OHPs) are lately considered as the superior light-harvesting materials for photodetectors owning to their unique advantages of high optical absorption coefficient, long exciton diffusion length, and low binding energy of exciton. [9][10][11] Although these OHP materials can be easily prepared by cost-effective solution-based processes to meet the ever-increasing consumer demands for large-area and flexible optoelectronics, their photodetectors usually exhibit the relatively low responsivity because of the limited carrier mobility as well as the absence of photoconductive gain (G) mechanism that can induce multiple charge carriers by one incident photon.In order to tackle these insufficient device performances, hybrid phototransistors by simply integrating perovskites (PVKs) with different 2D materials (e.g., graphene, [12] black phosphorus, [13,14] MoS 2 , [15] and WSe 2 [16] ) have been proposed and demonstrated. By using these hybrid heterostructures, upon illumination, the photoexcited charge carriers can be spatially separated at the hetero-interface in order to prolong their carrier lifetimes, which subsequently improves the photoconductive gain of the system. However, there are still significant concerns regarding the high fabrication cost and low production yield of 2D materials for the realization of such photodetectors. At the same time, due to the low formation energy, PVK photodetectors are generally susceptible to degradation upon air and moisture exposure. In this case, tremendous efforts have then been invested to explore effective approaches to enhance the ambient-stability of these devices. [17,18] Among many latest advances, recent breakthroughs in achieving the 2D Ruddlesden-Popper phase of PVKs with the chemical formula of (RNH 3 ) 2 (A) n−1 M n X 3n+1 , where RNH 3 is a large size or long-chain organic cation, A is a regular cation, M is a divalent Organic-inorganic hybrid perovskites (PVKs) have recently emerged as attractive materials for photodetectors. However, the poor stability and low electrical conductivity still restrict their practical utilization. Owing to the quantum-well feature of two-dimensional (2D) Ruddlesden-Popper PVKs (2D PVKs), a promising quasi-2D PVK/indium gallium zinc oxide (IGZO) heterostructure phototransistor can be designed. By using a simple ligand-exchange spin-coating method, quasi-2D PVK fabricated on flexible substrates exhibits a desirable type-II energy band alignment, which facilitates effect...

High‐Performance Quasi‐2D Perovskite/Single‐Walled Carbon Nanotube Phototransistors for Low‐Cost and Sensitive Broadband Photodetection

“…Such value is impressive even comparing to other reported perovskite‐based hybrid devices. [ 24,52–54 ] The gain ( G ), which represents how many effective photocarriers can be generated upon absorbing one photon, can be expressed in terms of responsivity as [ 1 ] where R , h , c , e , and λ are responsivity, Planck's constant, light speed, elementary charge, and wavelength of incoming light, respectively. The corresponding maximum gain for RPP/SWCNT device can be calculated to be 4.1 × 10 6 .…”

“…This is due to the much longer carrier lifetime in the devices caused by the gradient heterostructure in RPP film. [ 26,28,52 ] High gain photodetectors typically exhibit relatively slow response. [ 15,28 ] Incidentally, although the gain in MAPbI3/SWCNT device is much lower than that in RPP/SWCNT device, it is still higher or comparable to other MAPbI 3 ‐based hybrid phototransistors.…”

Emerging Perovskite Materials with Different Nanostructures for Photodetectors

“…Perovskite/indium gallium zinc oxide (IGZO) heterostruture phototransistors have also been reported recently. [ 131–135 ] Wei et al. fabricated a hybrid quasi‐2D perovskite/IGZO heterostructure phototransistor on a PET substrate.…”

Quantum Dot Enabled Perovskite Thin Film with Enhanced Crystallization, Stability, and Carrier Diffusion via Pulsed Laser Nanoengineering

“…Organic–inorganic hybrid perovskite has attracted much attention because of its excellent photoelectric properties such as long carrier lifetime, [ 1 ] long diffusion length, [ 2 ] and light absorption coefficient, [ 3 ] leading to broad applications in solar cells, [ 4 ] light‐emitting diodes, [ 5 ] photodetector, [ 6 ] and phototransistors, [ 7 ] etc. To perform high performance for perovskite‐based devices, structural and surface morphology optimization of perovskite, including grain structure, defects, compactness and surface affinity/hydrophobicity, play a crucial role in carrier transport dynamics, which is the key for high‐performance perovskite devices.…”