Abstract: The doping of colloidal halide perovskite nanocrystals (PNCs) with manganese cations (Mn2+) has recently enabled enhanced stability and novel optical properties and charge carrier dynamics in PNCs. However, the influence of Mn-doping on the synthetic routes and the band structures of the host PNCs has still not been clearly elucidated. Herein, we prove that Mn-doping promotes a facile, less toxic, and less corrosive path toward the synthesis of all-inorganic bismuth-based PNCs (Cs3Bi2I9) by effectively suppressing the CsI by-product of the Cs3BiI6 intermediate decomposition reaction. Furthermore, the energy levels of the as-formed Cs3Bi2I9 PNCs can be tuned upon different Mn-doping amounts. This results in a higher open-circuit voltage of the corresponding PNCs-based solar cells compared to those employing the undoped Cs3Bi2I9.

The heterovalent co-alloying of the B-site of perovskites has been also proposed as effective strategy to tune the optoelectronic properties of perovskites both in bulk and nanocrystals. Here, we demonstrate for the first time the alloying of lead (Pb) with titanium (Ti) as a successful approach to reduce the toxicity of PNCs and engineer their morphology and optical properties.

Our work opens new insights on the role of doping and co-alloying in the synthetic route and optoelectronic properties of halide PNCs with reduced toxicity.

Keywords: Halide perovskite nanocrystals, optoelectronic devices, colloidal synthesis, lead-free, doping, co-alloying.

Biography: Paola Vivo is an Associate Professor at Tampere University (TAU), Finland. After pursuing her Ph.D. in Chemistry with distinction, she received the Academy of Finland Fellowship for postdoctoral research in 2013‒2017. She has co-authored over 40 peer-reviewed publications (incl. Angew. Chem., Energy & Environmental Science, Small, etc). She currently leads the Hybrid Solar Cells research team (https://research.tuni.fi/hsc/) at the Faculty of Engineering and Natural Sciences at TAU. Her research interests include developing novel organic materials and hybrid organic-inorganic systems for third generation solar cells, with main emphasis on lead-free halide perovskites in bulk and nanocrystals.