In recent years, the already excellent optical properties of the inorganic lead-halide perovskite nanocrystals have been extended by means of doping. A remarkable finding was the result of doping the mixed halide perovskite CsPb(Cl/Br)3 with Yb3+ to achieve a photoluminescence quantum yield of the Yb3+ emission of nearly 200%. While this is highly promising for solar applications as downconverter layers on top of traditional silicon solar cells, unfortunately, this emission saturates orders of magnitude below AM1.5 intensities which presents a significant challenge for this material’s use in such layers. One of the possibilities to increase the emission saturation threshold is by incorporating more Yb3+ ions into the nanocrystals, but usually in wet chemical synthesis methods dopant concentrations are thermodynamically limited, putting an upper bound on the concentration of dopant ions that can be incorporated. Ball milling is a technique which can produce supersaturated alloys/solid-solutions of materials that normally don’t mix very well. The perovskite nanocrystals have been synthesized before by ball-milling, producing luminescent samples with high quantum yield. In this project, we attempt to synthesize Yb3+ doped CsPbX3 nanocrystals with different concentrations of Yb3+ by high-energy ball-milling and investigate its optical properties for down-conversion layers for photovoltaics.
You will explore the synthesis of these highly doped perovskite nanocrystals by our ball-milling setup, and measure the photophysical properties, among others to determine the Yb dopant concentration to optimize the synthesis.
Supervisor: Peter Schall, e-mail: firstname.lastname@example.org
Daily supervisors: Marco van der Laan, e-mail: email@example.com, and Ankit Goyal, e-mail: firstname.lastname@example.org