Beyond Doping: Complete Dopant Substitution in Two-Dimensional perovskite Nanoplatelets

Significance 

Two-dimensional perovskite nanoplatelets have been drawing much attention owing to their excellent properties which are favourable for device integration. In particular, cesium lead halide perovskite nanocrystals, a novel class of semiconductor materials with promising applications in optoelectronics. Moreover, the intentional incorporation of transition metal ions as dopants offers exciting opportunities to endow perovskite nanocrystals with novel optical, electronic, and magnetic functionalities. In line with this, numerous synthetic techniques have been developed for transition metal ion doped II−VI group semiconductor nanocrystals. Unfortunately, previous research has revealed that doping manganese ions into the perovskite nanocrystals is difficult; most likely due to the large size mismatch between the manganese ions dopant and the lead ions. Consequently, low doping efficiencies are achieved despite the high concentrations of dopants precursor introduced into the synthesis. Therefore, it is imperative that a novel strategy for efficient incorporation of dopants in advanced-shaped perovskite nanocrystals be developed.

Recently, a team of researchers at Syracuse University: Zhi-Jun Li, Elan Hofman, and Andrew Hunter Davis led by Dr. Weiwei Zheng from the Department of Chemistry in collaboration with Dr. Robert W. Meulenberg and Alex Khammang at Maine University, as well as Dr. Joshua T. Wright at Illinois Institute of Technology developed a simple solvothermal technique for efficient doping of manganese into 2D cesium lead chloride (Mn:CsPbCl3) perovskite nanoplatelets. In particular, they improved the doping efficiency through diffusion doping under solvothermal conditions. Their work is currently published in the research journal, Chemistry of Materials.

In brief, the research method employed commenced with the preparation of lightly doped 2D cesium lead chloride nanoplatelets under normal pressure and a relatively low temperature (120 °C). Next, the researchers synthesized heavily manganese doped cesium lead chloride nanoplatelets under solvothermal conditions at 200 °C in a Teflon-lined stainless-steel autoclave. They then characterized the resultant samples using transmission electron microscopy, powder X-ray diffraction analysis, electron paramagnetic resonance peak and X-ray absorption fine structure analysis.

The authors observed that the manganese doping efficiencies were strongly dependent on the solvothermal reaction temperature and time, which was further seen to affect the optical properties of the 2D manganese doped cesium lead chloride perovskite nanoplatelets. Additionally, they found a new cesium manganese chloride (CsMnCl3) phase with complete dopant substitution by spinodal decomposition with extended solvothermal treatment. Compared to manganese doped cesium lead chloride perovskite nanoplatelets, pure cesium manganese chloride perovskite nanoplatelets gave rise to shorter manganese photoluminescence lifetime, which was consistent with the short Mn−Mn distance within cesium lead chloride perovskite nanoplatelets.

“This new doping strategy offers a unique platform to investigate the change in structure and phase of doped 2D perovskite NCs and could offer new possibilities for property engineering of doped nanocrystals.” Zheng told Advances in Engineering.

In summary, Dr. Weiwei Zheng and his colleagues successfully demonstrated a facile solvothermal method for efficient diffusion doping in 2D manganese doped cesium lead chloride perovskite nanoplatelets. Further, the researchers here demonstrated the formation of a new cesium lead chloride perovskite phase by spinodal decomposition without significantly altering the morphology and size of host perovskite nanocrystals. This ability to incorporate a new phase by spinodal decomposition provided a novel understanding of doping inside quantum-confined nanocrystals. Altogether, their study offers an efficient strategy for doping inside nanocrystals as well as new insights on the dopant concentration-dependent structural and optical properties of perovskite nanocrystals.

Beyond Doping: Complete Dopant Substitution in Two-Dimensional perovskite Nanoplatelets - Advances in Engineering

About the author

Dr. Weiwei Zheng is an Assistant Professor in the Department of Chemistry at Syracuse University. He received his doctorate degree in Inorganic Chemistry from the Florida State University in 2011 under the supervision of Geoffrey F. Strouse. His graduate work focused on developing a fundamental understanding of the magnetic properties of transition metal ion-doped semiconductor quantum dots (QDs). In 2012, he joined the Emory University as a postdoctoral fellow to work with Khalid Salaita on the properties of hybrid organic/inorganic interfaces and biological applications of semiconductor nanocrystals. Zheng began his current appointment at Syracuse University in 2015.

His research interests include the synthesis and properties of novel functional nanomaterials for emerging applications in renewable energy and biological systems. He is particularly interested in the optical, electronic and magnetic properties of transition metal ion doped nanomaterials, selective surface functionalization of nanoparticles, hybrid nanocomposites, and the meso-scale assembly of 3-D nanoparticle superlattices.

About the author

Dr. Zhi-Jun Li obtained a Ph.D. degree in 2013 from the Technical Institute of Physics and Chemistry, CAS (China) under the direction of Prof. Li-Zhu Wu and Prof. Chen-Ho Tung. After he completed his Ph.D., he worked as a Research Scientist in Prof. Li-Zhu Wu and Prof. Chen-Ho Tung’s Lab from 2013 to 2016. His research was mainly focused on the synthesis and assembly methodologies for nanocrystal-based hybrid catalysts and their application for solar energy conversion. In 2017, he jointed Prof. Weiwei Zheng group in the Department of Chemistry at Syracuse University (USA) as a postdoctoral fellow.

His current research focuses on the synthesis and characterization of transition metal ion doped one-dimensional and two-dimensional semiconductor nanocrystals, and their application in optoelectronics and photocatalysis.

Reference

Zhi-Jun Li, Elan Hofman, Andrew Hunter Davis, Alex Khammang, Joshua T. Wright, Boris Dzikovski, Robert W. Meulenberg, Weiwei Zheng. Complete Dopant Substitution by Spinodal Decomposition in Mn Doped Two-Dimensional CsPbCl3 Nanoplatelets. Chemistry of Materials. 2018, volume 30, page 6400-6409.

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