Metal halide perovskites for blue and near-infrared light-emitting diodes
In his thesis, No Chen focuses on advancing the performance of perovskite light-emitting diodes (PeLEDs), specifically targeting the technologically crucial yet challenging blue and near-infrared (NIR) spectral regions. Chen employs strategic material and device engineering to overcome key limitations in film morphology, non-radiative recombination, and material instability.
For sky-blue emission, Chen developed a blade-coating strategy for CsPbBr₃ nanoplatelets (NPLs) embedded in a poly-TPD polymer matrix. By optimizing the NPL-to-polymer ratio and solution concentration, he achieved uniform, pinhole-free films, enabling the fabrication of large-area (16 mm²) blue PeLEDs with an external quantum efficiency (EQE) of 0.12%.
For NIR emission beyond 980 nm, Chen engineered mixed tin-lead (FA₀.₅MA₀.₅Sn₀.₅Pb₀.₅I₃) perovskites. The introduction of the 3-(aminomethyl)piperidinium (3-AMP) additive passivated defects, enhanced crystallinity, and extended carrier lifetime, resulting in PeLEDs with a pure emission peak at 988 nm and a peak EQE of 1.4%. Furthermore, Chen improved the perovskite/hole-transport layer interface by modifying PEDOT:PSS with a carbazole-based ammonium iodide derivative (4CzNH₃I), which enhanced wettability, reduced leakage current, and further boosted the EQE to 1.3%.
This work provides scalable fabrication methods and effective passivation strategies for high-performance PeLEDs across the visible and NIR spectrum.