A General Solvent Selection Strategy for Solution Processed Quantum Dots Targeting High Performance Light‐Emitting Diode

Abstract

An all‐solution‐processed quantum dots (QDs) light emitting diode (QLED) consists of different layers deposited from various orthogonal solvents. Here, the authors develop a general solvent selection strategy to obtain orthogonal solubility properties as well as high film quality. It is found that a “poor” QDs film morphology with striation defects often occurs when the QDs film is deposited from “bad” solvent. A physical model is presented to rationalize the observed striation defects, and then a general solvent selection strategy is proposed to prevent both surface striation defects and the dissolving of the underlying layers by carefully choosing the “good” solvent for QDs. A compact QDs film can be fabricated without altering the original morphology of underlying functional layers in a QLED device, leading to significant device performance improvement. An external quantum efficiency of 15.45% is achieved in a green QLED with uniform emitting region. This solvent selection strategy provides a general way to deposit high quality films for most of the solution‐processed multilayer optoelectronic devices.