All‐Solution‐Processed Perovskite Light‐Emitting Transistors Enabled by a Fully Organic Architecture

ABSTRACT CsPbBr 3 perovskite nanocrystals (Pe‐NCs) are promising solution‐processable emitters for light‐emitting devices due to their high brightness, color purity, and photoluminescence quantum yield. However, their integration into more advanced device architectures such as organic light‐emitting transistors (OLETs) remains limited by the lack of fully solution‐processable platforms that support uniform and compact Pe‐NCs emissive layers (EMLs). In this work, we report fully solution‐processed Pe‐NCs‐based LETs (Pe‐LETs) using CsPbBr 3 nanocrystals as the emitter. The realization of such a device is enabled by the development of a fully organic LET platform that incorporates: (i) a tailored bilayer gate dielectric of polyvinyl alcohol (PVA) and CyTOP, (ii) a solvent‐resistant p‐type polymer semiconductor, poly[2,5‐(2‐octyldodecyl)‐3,6‐diketopyrrolopyrrole‐alt‐5,5‐(2,5‐di(thien‐2yl)thieno[3,2‐b]thiophene)] (DPP‐DTT), and (iii) a nanocomposite EML of Pe‐NCs dispersed in a poly(9‐vinylcarbazole) and 1,3‐bis[2‐(4‐tert‐butylphenyl)1,3,4‐oxadiazo‐5‐yl]benzene (PVK:OXD‐7) matrix. Morphological and photophysical characterization, including confocal laser scanning microscopy, drives the optimization of solvent and processing conditions for uniform film formation. Benchmark device substructures are also used to fine‐tune the organic platform for effective EML integration. The resulting Pe‐LETs exhibit a narrow emission at 509 nm (full width at half maximum, FWHM = 19.2 nm), demonstrating excellent color purity suitable for displays and sensing. A maximum external quantum efficiency of 4.17 × 10 − 3 % is achieved, comparable to state‐of‐the‐art values for inorganic‐based LETs.