Search

Abstract Unbalanced mobility and injection of charge carriers in metal‐halide perovskite light‐emitting devices pose severe limitations to the efficiency and response time of the electroluminescence. Modulation of gate bias in methylammonium lead iodide light‐emitting transistors has proven effective in increasing the brightness of light emission up to MHz frequencies. In this work, a new approach is developed to improve charge carrier injection and enhance electroluminescence of perovskite light‐emitting transistors by independent control of drain–source and gate–source bias voltages to compensate for space‐charge effects. Optimization of bias pulse synchronization induces a fourfold enhancement of the emission intensity. Interestingly, the optimal phase delay between biasing pulses depends on modulation frequency due to the capacitive nature of the devices, which is well captured by numerical simulations of an equivalent electrical circuit. These results provide new insights into the electroluminescence dynamics of AC‐driven perovskite light‐emitting transistors and demonstrate an effective strategy to optimize device performance through independent control of the amplitude, frequency, and phase of the biasing pulses.

Light-emitting transistors (LETs) have attracted tremendous academic and industrial interest due to their dual functions of electrical switching and light emission in a single device, which can considerably reduce system complexity and manufacturing costs, especially in the area of flat panel and flexible displays as well as lighting and lasers. In recent years, enhanced LET performance has been achieved by introducing multiple-layer heterostructures in the charge-carrying/light-emitting LET channel versus the best-reported performance in single active layer LETs, rendering multi-layer LETs promising candidates for next-generation display technologies. In this review, the fundamental structures and working principles of multi-layer heterostructure LETs are introduced. Next, developments in multi-layer LETs are discussed based on co-planar LETs, non-planar LETs, and vertical LETs including organic, quantum dot, and perovskite light emitters. Finally, this review concludes with a summary and a perspective on the future of this research field., (© 2021 Wiley-VCH GmbH.)

Light-emitting transistors (LETs) have attracted a significant amount of interest as multifunctional building blocks for next-generation electronics and optoelectronic devices. However, it is challenging to obtain LETs with a high carrier mobility and uniform light-emission because the semiconductor channel should provide both the electrical charge transport and optical light-emission, and typical emissive semiconductors have low, imbalanced carrier mobilities. In this work, a novel device platform that adapts the electrochemiluminescence (ECL) principle in LETs, referred to as an ECL transistor (ECLT) is proposed. ECL is a light-emission phenomenon from electrochemically excited luminophores generated by redox reactions. A solid-state ECL electrolyte consisting of a network-forming polymer, ionic liquid, luminophore, and co-reactant is employed as the light-emitting gate insulator of the ECLT. Based on this construction, high-performance LETs that make use of various conventional non-emissive semiconductors (e.g., poly(3-hexylthiophene), zinc oxide, and reduced graphene oxide) are successfully demonstrated. All the devices exhibit a high mobility (0.9-10 cm 2 V -1 s -1 ) and a uniform light-emission. This innovative approach demonstrates a novel LET platform and provides a promising pathway to achieve significant breakthroughs to develop electronic circuits and optoelectronic applications., (© 2020 Wiley-VCH GmbH.)

2D semiconductors have shown great potential for application to electrically tunable optoelectronics. Despite the strong excitonic photoluminescence (PL) of monolayer transition metal dichalcogenides (TMDs), their efficient electroluminescence (EL) has not been achieved due to the low efficiency of charge injection and electron-hole recombination. Here, multioperation-mode light-emitting field-effect transistors (LEFETs) consisting of a monolayer WSe 2 channel and graphene contacts coupled with two top gates for selective and balanced injection of charge carriers are demonstrated. Visibly observable EL is achieved with the high external quantum efficiency of ≈6% at room temperature due to efficient recombination of injected electrons and holes in a confined 2D channel. Further, electrical tunability of both the channel and contacts enables multioperation modes, such as antiambipolar, depletion,and unipolar regions, which can be utilized for polarity-tunable field-effect transistors and photodetectors. The work exhibits great potential for use in 2D semiconductor LEFETs for novel optoelectronics capable of high efficiency, multifunctions, and heterointegration., (© 2020 Wiley-VCH GmbH.)

The past several years have witnessed tremendous developments of metal halide perovskite (MHP)-based optoelectronics. Particularly, the intensive research of MHP-based light-emitting diodes, photodetectors, and solar cells could probably reform the optoelectronic semiconductor industry. In comparison, in spite of the large intrinsic charge carrier mobility of MHPs, the development of MHP-based field-effect transistors (MHP-FETs) is relatively slow, which is essentially due to the gate-field screening effect induced by the ion migration and accumulation in MHP-FETs. This work mainly aims to summarize the recent important work on MHP-FETs and propose solutions in terms of the development bottleneck of perovskite-based transistors, in an attempt to boost the research of MHP transistors further. First, the advantages and potential applications of MHP-FETs are briefly introduced, which is followed by a detailed description of the MHP crystalline structure and various material fabrication techniques. Afterward, MHP-FETs are discussed, including transistors based on hybrid organic-inorganic perovskites, all-inorganic perovskites, and lead-free perovskites., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Following the unprecedented rise in photovoltaic power conversion efficiencies during the past five years, metal-halide perovskites (MHPs) have emerged as a new and highly promising class of solar-energy materials. Their extraordinary electrical and optical properties combined with the abundance of the raw materials, the simplicity of synthetic routes, and processing versatility make MHPs ideal for cost-efficient, large-volume manufacturing of a plethora of optoelectronic devices that span far beyond photovoltaics. Herein looks beyond current applications in the field of energy, to the area of large-area electronics using MHPs as the semiconductor material. A comprehensive overview of the relevant fundamental material properties of MHPs, including crystal structure, electronic states, and charge transport, is provided first. Thereafter, recent demonstrations of MHP-based thin-film transistors and their application in logic circuits, as well as bi-functional devices such as light-sensing and light-emitting transistors, are discussed. Finally, the challenges and opportunities in the area of MHPs-based electronics, with particular emphasis on manufacturing, stability, and health and environmental concerns, are highlighted., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Area emission is realized in all-solution-processed hybrid light-emitting transistors (HLETs). A new HLET design is presented with increased aperture ratio, and optical and electrical characteristics are shown., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)