Lanthanide doping in metal halide perovskite nanocrystals: spectral shifting, quantum cutting and optoelectronic applications

• Published in: NPG Asia materials Vol. 12; no. 1
• Main Authors: Mir, Wasim J., Sheikh, Tariq, Arfin, Habibul, Xia, Zhiguo, Nag, Angshuman
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 24.01.2020; Nature Publishing Group
• Subjects: 639/638/298/398; 639/925/357/1017; Biomaterials; Cadmium selenides; Chemistry and Materials Science; Coordination; Crystal lattices; Cutting; Dopants; Doping; Electron transitions; Energy; Energy Systems; High energy electrons; Lanthanides; Lanthanum; Lead free; Material properties; Materials Science; Metal halides; Nanocrystals; Nanoparticles; Optical activity; Optical and Electronic Materials; Optical lattices; Optical properties; Optoelectronics; Perovskites; Photoluminescence; Photonic band gaps; Photons; Photovoltaic cells; Review Article; Semiconductors; Structural Materials; Surface and Interface Science; Thin Films
• ISSN: 1884-4049; 1884-4057
• DOI: 10.1038/s41427-019-0192-0

Lanthanides have been widely explored as optically active dopants in inorganic crystal lattices, which are often insulating in nature. Doping trivalent lanthanide (Ln 3+ ) into traditional semiconductor nanocrystals, such as CdSe, is challenging because of their tetrahedral coordination. Interestingly, CsPbX 3 (X = Cl, Br, I) perovskite nanocrystals provide the octahedral coordination suitable for Ln 3+ doping. Over the last two years, tremendous success has been achieved in doping Ln 3+ into CsPbX 3 nanocrystals, combining the excellent optoelectronic properties of the host with the f-f electronic transitions of the dopants. For example, the efficient quantum cutting phenomenon in Yb 3+ -doped CsPb(Cl,Br) 3 nanocrystals yields a photoluminescence quantum yield close to 200%. Other approaches of Ln 3+ doping and codoping have enabled promising proof-of-principle demonstration of solid-state lighting and solar photovoltaics. In this perspective article, we highlight the salient features of the material design (including doping in Pb-free perovskites), optical properties and potential optoelectronic applications of lanthanide-doped metal halide perovskite nanocrystals. While review articles on doping different metal ions into perovskite nanocrystals are present, the present review-type article is solely dedicated to lanthanide-doped metal halide perovskite nanocrystals. Optoelectronics: A helping hand across the gap Methods for integrating lanthanide materials into light-emitting devices to improve their performance have been reviewed by scientists from India and China. Semiconductors create light when the energy of a high-energy electron is converted to a single photon. Conventionally, the minimum energy of this photon is determined by an intrinsic material property known as the bandgap. Wasim Mir from the Indian Institute of Science Education and Research Pune, and colleagues, summarize developments in using lanthanide ions to enable the generation of lower-energy light. Lanthanide ions provide an energy “step” within the bandgap that means the electron is converted to two low energy photons rather than a single high energy one. The authors review how embedding lanthanum ions within nanoparticles made from so-called metal-halide perovskites makes them easier to integrate into common optoelectronic semiconductors such as silicon. Metal halide perovskites are extraordinary defect-tolerant semiconductors. A unique structural aspect of perovskites is the octahedral coordination for (B-site) metal ions, unlike other semiconductors that exhibit tetrahedral coordination. This octahedral coordination helped to achieve lanthanide doping in halide perovskite nanocrystals in 2017. Fundamental understanding of material design, luminescence and quantum cutting phenomena in lanthanides (with focus on Yb 3+ ) doped in CsPbX 3 (X = Cl, Br, I) and Cs 2 AgInCl 6 nanocrystals are reported. Subsequently, these doped systems are applied for solar energy harvesting and lighting in both visible and near infrared region. This perspective article summarizes everything important that has happened so far in field and discusses about the future research directions.