Coffee‐Stain‐Free Perovskite Film for Efficient Printed Light‐Emitting Diode. Issue 17 (14th June 2021) - Li, Ya
Abstract: Inkjet printing is a powerful technology for realizing high‐density pixelated perovskite light‐emitting diodes (PeLEDs). However, the coffee‐stain effect in the inkjet printing process often leads to uneven thickness and poor crystallization of printed perovskite features, which deteriorates the performance of PeLEDs. Here, a strategy is developed to suppress the coffee‐stain effect via enhancing Marangoni flow strength. An interfacial poly(vinylpyrrolidone) (PVP) layer is incorporated to tune the surface tension of the underlying hole transport layer (HTL) and enhance the perovskite crystallization. The substrate temperature is also carefully controlled to tune the printing solvent evaporation rate rationally. By optimizing the thickness of the PVP layer and the temperature of the printing stage, the coffee‐stain effect is dramatically restrained. In addition, the interfacial insulating PVP layers play a positive role in suppressing leakage current level of PeLEDs by avoiding any direct electrical contact between HTL and electron transporting layer. Finally, an inkjet‐printed PeLED with a brightness of 3640 cd m –2 and external quantum efficiency of 9.0% is achieved. This work highlights the availability of inkjet‐printing technology for fabricating patterned PeLEDs in information display applications. Abstract : A facile strategy is developed to achieve high‐quality perovskite light emitting diode (PeLED) by inkjet‐printing perovskite precursor solution. Here, by incorporating an interface polyvinylpyrrolidone layer and adjusting the temperature of the printing substrate, the coffee‐stain effect is effectively inhibited. Finally, an inkjet‐printed PeLED with a brightness of 3640 cd m –2 and external quantum efficiency of 9.0% was achieved.