Semiconducting nanocrystals (NCs) have a broad application in optoelectronics (such as solar cells, LEDs, lasers, and photodetectors), biomedical imaging, and photocatalysis. The Nobel Prize in Chemistry 2023 has recently highlighted the breakthrough discovery and synthesis of nanometer-sized semiconducting crystals.
Recently, materials with perovskite-like crystal structure, i.e., inspired to that of CaTiO3 crystal, the archetype perovskite, emerged as an appealing option for such applications due to their outstanding physical properties. Moreover, the versatile colloidal synthesis method can be applied to synthesize the perovskite-based nanomaterials. However, perovskite and perovskite-inspired nanocrystals still lack stability and raise toxicity concerns due to the presence of lead (Pb) in the most promising compositions.
New knowledge on lead-free perovskite alternatives
In her doctoral dissertation, consisting of four publications, Matiukhina provides new knowledge in the area of perovskite nanocrystals.
Her first publication contributed to the improvement of the phase stability of CsPbI3 NCs. CsPbI3 NCs are being utilized as photoactive material in solar cells and LEDs, due to outstanding light harvesting and emitting properties. However, their poor stability, leading to fast decomposition in ambient conditions, diminishes their practical application potential. As one of its major efforts the research community aims at enhancing the stability of perovskite NCs using a variety of synthetic approaches.
“The correlation between the phase stability of CsPbI3 NCs and the reaction temperature was identified which, in turn contributed to significantly improved stability of the corresponding solar cells,” says Matiukhina.
CsMnCl3 NCs were recently reported as a substantially eco-friendlier alternative to CsPbI3 in the domain of red-light emitters. However, since controversial photoluminescence properties of CsMnCl3 NCs have been previously documented, Matiukhina’s second publication targeted the unravelling of the relationship between the emitting properties of the CsMnCl3, phase formation, and synthesis conditions.
“As a result, the unique optical properties of CsMnCl3 NCs were exploited to demonstrate proof-of-concept NC-based luminescent solar concentrators, i.e., devices that collect the light from a large area and reemit it to tiny solar cells, allowing the electricity generation with minimized solar cell area,” she explains.
In her third publication Matiukhina investigated further lead-free perovskite alternatives and demonstrated the first-ever colloidal synthesis of Cs2TiBr/Cl6 NCs. The optical properties, stability, and nonlinear applications of this new family of sustainable semiconductors were outlined.
In the fourth publication she provided insights into the surface properties of new emerging perovskite-inspired materials, namely AgBiI4 NCs. The relationship between the NCs surface, the optoelectronic properties, and stability was investigated through a comprehensive set of experimental and theoretical methods, to ultimately identify the optimal NC surface in terms of electronic structure and stability.
Public defence on Friday 24 November
The doctoral dissertation of M.Sc. Anastasiia Matiukhina in the field of physics titled Halide perovskite and perovskite-inspired nanocrystals for optoelectronic applications will be publicly examined at the Faculty of Engineering and Natural Science of Tampere University at Hervanta Campus in Festia building in the auditorium FA032 Pieni sali 1 (Korkeakoulunkatu 8, Tampere) at 12 o’clock on Friday 24 November 2023. The Opponent will be Professor Aldo Di Carlo, University of Rome Tor Vergata, Italy. The Custos will be Associate Professor (tenure-track) Paola Vivo, Tampere University, Finland.