CdCl2后处理的Mn掺杂钙钛矿纳米晶光学性能及其白光LED

Optical Properties and White LED of Mn Doped Perovskite Nanocrystals after CdCl2 Treatment

摘要:

Mn²⁺离子掺杂全无机钙钛矿(Mn²⁺∶CsPbX₃,X=Cl,Br)纳米晶(NCs)具有宽发射带、长斯托克斯位移和高量子产率等优势,在固态照明、光电探测和成像等领域有广阔应用前景。然而,目前Mn²⁺掺杂的钙钛矿晶体量子产率很难超过70%,如何改善发光效率,同时调控Mn离子发射中心成为构建高质量白光LED的关键。文章通过CdCl₂后处理技术,进行室温下阳离子交换,获得了高效发光的Cd²⁺和Mn²⁺共掺杂的CsPbCl₃纳米晶。Mn的发射波长可以从604nm连续调控到624nm,实现稳定的红光发射。Cd离子掺杂改善了Mn-Cl八面体的晶体场环境,使Mn衰减寿命提高到1.32ms。此外,通过绿色CsPbBr₃纳米晶和蓝-橙双色Mn∶CsPb(ClBr)₃纳米晶构建了高显色指数的暖白光发光二极管(WLED),其流明效率达60lm/W,显色指数超过85。

Abstract:

Mn²⁺ ion doped all-inorganic perovskite (Mn²⁺∶CsPbX₃, X=Cl,Br) nanocrystals have been promising for a wide range of applications in solid-state lighting, photoelectric detection and imaging due to their advantages of wide emission bands, long Stokes shifts and high quantum yields. However, the quantum yield of Mn²⁺-doped perovskite crystals hardly exceeds 70%. How to improve the luminous efficiency while regulating the Mn ion emission centers becomes the key to build high-quality white LEDs. In this paper, highly efficient luminescent Cd²⁺ and Mn²⁺ co-doped CsPbCl₃ nanocrystals were obtained by CdCl₂ post-treatment technique with cation exchange at room temperature. The emission wavelength of Mn can be continuously tuned from 604nm to 624nm to achieve stable red light emission. Cd ion doping improves the crystal field environment of Mn-Cl octahedra and increases the Mn decay lifetime to 1.32ms. In addition, warm white light-emitting diodes (WLEDs) with high color rendering index were constructed by green CsPbBr₃ nanocrystals and blue-orange bicolor Mn∶CsPb(ClBr)₃ nanocrystals. The lumen efficiency reaches 60lm/W and the color rendering index exceeds 85.