Showing papers by "Shufen Chen published in 2022"

Efficient Pure Blue Light-Emitting Diodes Based on CsPbBr3 Quantum-Confined Nanoplates.

Abstract: Exploitation of next-generation blue light-emitting diodes (LEDs) is the foundation of the revolution in lighting and display devices. Development of high-performance blue perovskite LEDs is still challenging. Herein, 4-aminobenzenesulfonic acid (SA) is introduced to passivate blue CsPbBr3 nanoplates (NPLs), reducing the ionic migration via a more stable Pb2+-SO3-- formation, and the trap state density of films shows a 50% reduction. The inevitable Br- vacancy defects after the multistep washing process can be suppressed by a suitable MABr treatment, which can boost the external quantum efficiency (EQE) performance. It should be noted that the coverage of NPL films is another key factor to realize reproducible pure blue electroluminescence (EL). Therefore, we proposed an alternate droplet/spin coating method to improve the coverage and thickness of NPL layer to prevent hole transport layer emission and increase the reproducibility of LED performance and spectra. Furthermore, we designed hole transport layers to decrease the hole transport barrier and improve the energy-level alignment. According to SA passivation, MABr treatment, alternate droplet/spin coating method, and device structure optimization, a CsPbBr3 NPL-based pure blue (0.138, 0.046) LED with 3.18% maximum EQE can be achieved, and the half-lifetime of EL can be enhanced 1.71 times as compared to that of the counterpart LED without SA. Both performance and stability of pure blue NPL LEDs can be greatly improved via ligand passivation, alternate droplet/spin coating method, and device structure optimization, which is a trend to promote the development of pure blue perovskite LEDs in future.

Gridization‐Driven Mesoscale Self‐Assembly of Conjugated Nanopolymers into Luminescence‐Anisotropic Photonic Crystals

Abstract: Organic semiconducting emitters integrated with butterfly‐mimetic photonic crystals (PhCs) are fascinating for dramatic advantages over light outcoupling efficiency and multifunctional strain sensors, as well as the key step toward electrically pumped lasers. Herein, an unprecedentedly direct mesoscale self‐assembly into 1D PhCs is reported through a covalently gridization‐driven approach of wide‐bandgap conjugated polymers. A simple solvent‐casting procedure allows for in situ self‐assembly of the state‐of‐the‐art conjugated nanopolymer, poly{[4‐(octyloxy)‐9,9‐diphenylfluoren‐2,7‐diyl]grid}‐co‐{[5‐(octyloxy)‐9,9‐diphenylfluoren‐2,7‐diyl]grid} (PODPFG), into well‐defined multilayer architectures with an excellent toughness (30–40 J m–3). This ordered meso‐architecture shows a typical Bragg–Snell diffraction behavior to testify the PhC nature, along with a high effective refractive index (1.80–1.88) and optical transmittance (85–87%). The PhC films also exhibit an angle‐dependent blue/green photoluminescence switching, an electroluminescence efficiency enhancement by 150–250%, and an amplified spontaneous emission enhancement with ultralow waveguide loss coefficient (2.60 cm–1). Gridization of organic semiconductors offers promising opportunities for cross‐scale morphology‐directed molecular design in multifunctional organic mechatronics and intelligences.