image: a, structure of LED based on PeNCs without and with passivation. Schematic illustrates that CP could passivate defects, in which the defects may trap carriers (e.g. holes, electrons), decrease exciton recombination, and hence degrade the device performances. b, Schematic and energy-level diagrams of the Ln³⁺ ion-doped CsPbCl₃ LED configuration. c, Simplified energy-level diagram of Ln³⁺ ion luminescence process and corresponding EL spectra for the LEDs based on these Ln³⁺ ions doped CsPbCl₃ PeNCs. view more
Credit: by Rui Sun, Donglei Zhou, Yujiao Ding, Yue Wang, Yuqi Wang, Xinmeng Zhuang, Shuainan Liu, Nan Ding, Tianyuan Wang, Wen Xu, Hongwei Song
Lead halide perovskite nanocrystals (PeNCs) have attracted extensive attention due to their high photoluminescence quantum yield (PLQY), adjustable bandgap, low cost, and excellent photoelectric properties. In recent years, perovskite based light emitting diodes (LEDs) have developed rapidly and become candidates for low-cost, solution-processing based solid-state lighting. White light perovskite LEDs are possible to be obtained by stacking different NCs with complementary emissions together in one film. However, the halide ion segregation and exchange lead to severe color instability and complex structure in mixed halide perovskite LED devices. Therefore, new ideas and technologies are required for the development of white light devices.
In a new paper published in Light: Science & Application, a team of scientists, led by Professor Hongwei Song from State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, China, and co-workers have developed a promising method to fabricate white perovskite LEDs using lanthanides (Ln3+) ions doped CsPbCl3 PeNCs. Based on Förster-Dexter theory, the bandgap of perovskite host need to be regulated to match with the energy levels of Ln3+ ions considering the different 4f electronic configurations. And specific defect passivation by introducing stronger binding capping ligands is an important approach to improve the performance of PeNC film. Afterwards, the perovskite LEDs based on the Ln3+ ions doped PeNCs experiencing band engineering and defect passivation were fabricated, in which the EL of Ce3+, Er3+, Sm3+, Eu3+ ions are successfully obtained, respectively. More importantly, the LEDs based 3.5 mol% Eu3+ ions doped PeNCs show the white light emitting, a peak luminance of 1678 cd m-2 and a maximum external quantum efficiency (EQE) of 5.4%, demonstrating excellent performance among existing white PeNCs LEDs from single chip. This work demonstrates the superiority of single-component Ln3+ ions doped perovskite in the realization of highly efficient and stable white LEDs, providing the optimal scheme for the development of low-cost, simple-structure white perovskite LEDs.
Journal
Light Science & Applications
Article Title
Efficient single-component white light emitting diodes enabled by lanthanide ions doped lead halide perovskites via controlling Förster energy transfer and specific defect clearance
Article Publication Date
6-Dec-2022