Full color quantum dot light‐emitting diodes patterned by photolithography technology

Abstract Quantum dot light‐emitting diodes are promising candidates for next generation displays. For display application, a pixel consists of red (R), green (G), and blue (B) side‐by‐side sub‐pixels, which thereby requires a high resolution patterning of the light‐emission layers. In this work, the quantum dot (QD) light‐emitting layers are fine patterned by using the photolithography and the lift‐off techniques. To facilitate the lift‐off process, reverse photoresist AZ5214E is used because of its special inverted trapezoidal structure after developing. To prevent the QDs being washed off during the lift‐off process, the ZnMgO layer is treated by the hydrophobic material hexamethyldisilazane. With hexamethyldisilazane treatment, the adhesion between the QDs and the ZnMgO is effectively improved. As a result, side‐by‐side R/G/B QD with pixel size of 30 μm × 120 μm is successfully achieved. After patterning, the R, G, and B‐quantum dot light‐emitting diodes exhibit a maximum current efficiency of 11.6 cd/A, 29.7 cd/A, and 1.5 cd/A, respectively. This work confirms the feasibility of patterning QDs by using the photolithography and the lift‐off techniques.