Ijaz Palvasha, Imran Muhammad, Soares Márcio M, Tolentino Hélio C N, Martín-García Beatriz, Giannini Cinzia, Moreels Iwan, Manna Liberato, Krahne Roman
Dipartimento di Chimica e Chimica Industriale, Università degli Studi di Genova, Via Dodecaneso 31, 16146 Genova, Italy.
Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP 13083-970, Brazil.
J Phys Chem Lett. 2020 Mar 19;11(6):2079-2085. doi: 10.1021/acs.jpclett.0c00266. Epub 2020 Mar 3.
The photoluminescence (PL), color purity, and stability of lead halide perovskite nanocrystals depend critically on surface passivation. We present a study on the temperature-dependent PL and PL decay dynamics of lead bromide perovskite nanocrystals characterized by different types of A cations, surface ligands, and nanocrystal sizes. Throughout, we observe a single emission peak from cryogenic to ambient temperature. The PL decay dynamics are dominated by surface passivation, and a postsynthesis ligand exchange with a quaternary ammonium bromide (QAB) results in more stable passivation over a larger temperature range. The PL intensity is highest from 50 to 250 K, which indicates that ligand binding competes with the thermal energy at ambient temperature. Despite the favorable PL dynamics of nanocrystals passivated with QAB ligands (monoexponential PL decay over a large temperature range, increased PL intensity and stability), surface passivation still needs to be improved to achieve maximum emission intensity in nanocrystal films.
卤化铅钙钛矿纳米晶体的光致发光（PL）、色纯度和稳定性严重依赖于表面钝化。我们对以不同类型的A阳离子、表面配体和纳米晶体尺寸为特征的溴化铅钙钛矿纳米晶体的温度相关PL和PL衰减动力学进行了一项研究。在整个过程中，我们观察到从低温到环境温度都有一个单一的发射峰。PL衰减动力学主要由表面钝化主导，并且用溴化季铵盐（QAB）进行合成后配体交换会在更大的温度范围内导致更稳定的钝化。PL强度在50至250 K时最高，这表明配体结合在环境温度下与热能相互竞争。尽管用QAB配体钝化的纳米晶体具有良好的PL动力学（在较大温度范围内单指数PL衰减、PL强度增加和稳定性提高），但仍需要改进表面钝化以在纳米晶体薄膜中实现最大发射强度。
