Recent Advances in Multi‐Layer Light‐Emitting Heterostructure Transistors

Abstract

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.

Structures, Properties, and Device Applications for [1]Benzothieno[3,2‐b]Benzothiophene Derivatives

“…In the past few years, BTBT and its derivatives materials gradually applied to organic light‐emitting transistors (OLETs). [ 257–260 ] In 2017, Namdas et al. applied two BTBT derivatives C10‐BTBT and Ph‐BTBT‐C10 to prepare OLETs with emission in the narrow UV and deep blue range ( Figure a).…”

“…In the past few years, BTBT and its derivatives materials gradually applied to organic light-emitting transistors (OLETs). [257][258][259][260] In 2017, Namdas et al applied two BTBT derivatives C10-BTBT and Ph-BTBT-C10 to prepare OLETs with emission in the narrow UV and deep blue range (Figure 14a). [261] C8-BTBT was also used in OLETs to serve as the hole transport layer because of its high mobility, wide band gap, and suitable HOMO and LUMO level.…”

Organic Light‐Emitting Transistors in a Smart‐Integrated System for Plasmonic‐Based Sensing

“…TPBi and Cs 2 CO 3 were used as electron injecting layers. According to state‐of‐the‐art OLETs, [ 52 ] nonplanar source (70 nm) and drain (20 nm) electrodes were deposited in direct contact of the C8‐BTBT and onto the stacked multilayer, respectively. Organic layers and electrodes were deposited by thermal evaporation in a high‐vacuum deposition chamber at a base pressure of 10 −8 mbar using shadow masks.…”

En Route to Wide Area Emitting Organic Light‐Emitting Transistors for Intrinsic Drive‐Integrated Display Applications: A Comprehensive Review

“…The operating mode of these device architectures not only depends on the applying bias voltages but also on the type of charge carrier, such as nor p-or ambipolar type, and their detailed descriptions were found elaborately in recently reported reviews. [27,66,72,73] Briefly, by applying the negative or positive bias voltages, the high or low work function electrodes inject the hole or electron carriers into the transistor channel, respectively. The injected charge carrier was transported to the active layer and meet the opposite charge carrier at a specific location (RZ) of the channel to form excitons that can radiatively recombine as light emission.…”

“…Recent developments and perspectives in device configurations, charge transport, and emitting materials for OLET were reviewed by eminent research groups over this decade. [27,28,61,62,[64][65][66][67][68][69][70][71][72] Those reviews were classified based on i) device configurations such as unipolar and ambipolar OLET, single, bi-, multilayer, or bulk heterojunction architecture, ii) asymmetric work function electrode contacts, non-planar source-drain contacts, (iii) type of charge transporting materials, and emitting materials such as fluorescent, phosphorescent, and thermally activated delayed fluorescence (TADF) materials, polymers, perovskites, and quantum dot materials, transition metal dichalcogenides, single crystals, iv) dielectrics [73] and other directions such as vertical OLET, carbon nanotube OLET, electrolyte gated OLET [74] and alternating-current operating OLET (AC). The present review mainly emphasizes the luminescent characteristics of OLET by systematically analyzing the key device/molecular engineering tactics that assisted in improving the electrode edge narrow emission to wide-area pixel emission.…”