Affiliation:
1. State Key Laboratory of Luminescent Materials and Devices and Guangdong Basic Research Center of Excellence for Energy & Information Polymer Materials South China University of Technology Wushan Road 381 Guangzhou 510640 P. R. China
2. College of Chemistry and Chemical Engineering Key Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Province Shantou University Guangdong 515063 P. R. China
3. Laboratory of Advanced Optoelectronic Materials Suzhou Key Laboratory of Novel Semiconductor‐optoelectronics Materials and Devices College of Chemistry Chemical Engineering and Materials Science Soochow University Suzhou 215123 P. R. China
Abstract
AbstractMixed halide perovskites are widely investigated as emitters for efficient light‐emitting diodes owing to their excellent optoelectronic properties. Compared with red and green emissions, encouraging progress in efficiency for blue emission has only been achieved in sky‐blue region. A high Cl/Br ratio is indispensable to achieve deep‐blue emission, which often leads to pronounced halogen migration in perovskite light‐emitting diodes (PeLEDs) and thus diminished efficacy. To avoid the negative effects of excessive chloride necessary to achieve deep‐blue emission, alloyed perovskite quantum dotes (QDs) passivated by dual‐functional guanidine sulfamate are synthesized, where S═O of sulfamate coordinates with Pb, and guanidine can form N‐H‐X (Cl/Br) with halogen ions to complete passivation. As a result, deep‐blue emission is achieved for the alloyed perovskite QDs. Owing to the suppressed defects and the reduced surface electrostatic potential of the perovskite QDs film, the carrier recombination region in the PeLEDs is regulated. Finally, deep‐blue PeLEDs with a spectrally stable electroluminescence peak at 458 nm, peak external quantum efficiency of 3.65% and maximum brightness of 223 cd m−2 are realized.
Funder
National Key Research and Development Program of China
National Natural Science Foundation of China