Liu Zheming, Zito Juliette, Ghini Michele, Goldoni Luca, Prato Mirko, Bahmani Jalali Houman, Infante Ivan, De Trizio Luca, Manna Liberato
Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, Via Dodecaneso 31, 16146 Genova, Italy.
Nano Lett. 2022 Nov 9;22(21):8567-8573. doi: 10.1021/acs.nanolett.2c03112. Epub 2022 Oct 26.
We show how, in the synthesis of yellow-emissive Bi-doped CsAgNaInCl double perovskite nanocrystals (NCs), preventing the transient formation of Ag particles increases the photoluminescence quantum yield (PLQY) of the NCs from ∼30% to ∼60%. Calculations indicate that the presence of even a single Ag species on the surface of a NC introduces deep trap states. The PL efficiency of these NCs is further increased to ∼70% by partial replacement of Na with K ions, up to a 7% K content, due to a lattice expansion that promotes a more favorable ligands packing on the NC surface, hence better surface passivation. A further increase in K lowers the PLQY, due to both the activation of nonradiative quenching channels and a lower oscillator strength of the BiCl→AgCl transition (through which PL emission occurs). The work indicates how a deeper understanding of parameters influencing carrier trapping/relaxation can boost the PLQY of double perovskites NCs.
我们展示了在合成黄色发光的铋掺杂CsAgNaInCl双钙钛矿纳米晶体（NCs）时，防止银颗粒的瞬态形成如何将NCs的光致发光量子产率（PLQY）从约30%提高到约60%。计算表明，即使在NC表面存在单个银物种也会引入深陷阱态。通过用钾离子部分替代钠，钾含量高达7%，由于晶格膨胀促进了NC表面更有利的配体堆积，从而实现更好的表面钝化，这些NCs的PL效率进一步提高到约70%。钾含量的进一步增加会降低PLQY，这是由于非辐射猝灭通道的激活以及BiCl→AgCl跃迁（通过该跃迁发生PL发射）的较低振子强度。这项工作表明，对影响载流子俘获/弛豫的参数有更深入的理解如何能够提高双钙钛矿NCs的PLQY。
