Multilayer heterostructure engineering for high-purity and uniform area emission in perovskite quantum-dot light-emitting transistors

Abstract

Light-emitting transistors (LETs) represent a promising device that integrates electrical switching with light emission, yet their development is fundamentally limited by the edge-localized electroluminescence confined near the drain electrode and poor color purity. Here, we demonstrate a solution-processed multilayer perovskite quantum-dot-based LET (QD-LET), enabling high color purity and uniform area emissive operation by a synergistic nano-interface engineering strategy. By strategically incorporating poly(9-vinylcarbazole) (PVK) as an electron-blocking interlayer and an ultrathin Al₂O₃ charge-modulation layer between the high-mobility Zn–Sn–O (ZTO) channel and the colloidal CsPbX₃ (X = Cl, Br, or I) quantum-dot layer, the carrier injection is effectively balanced and the interfacial electron distribution beneath the drain electrode is homogenized. The PVK and Al₂O₃-modified layer cooperatively modulates the minority carrier injection barrier and redistributes the induced majority carriers in the channel, transitioning the device from conventional edge-localized emission to uniform mm²-scale area emission. Consequently, the QD-LETs achieve Rec.2020-level color purity with ultranarrow emission linewidths (an FWHM of 25 nm for green) and stable CIE coordinates. Furthermore, the optimized device maintains superior transistor characteristics, including an electron mobility of 4.7 cm² V⁻¹ s⁻¹ and an I_on/I_off ratio > 10⁵. This work provides fundamental insights into interfacial charge dynamics in multilayer optoelectronic devices and establishes a scalable pathway for spectrally precise, large-area perovskite display technologies.