[staff-physics-and-astronomy-HL-UHD-UD] Canceled: Seminar - PhotoConversion Materials - Artem Bakulin

[Beta NAT Secretariaat]

Artem Bakulin - Short Bio
His research focuses on the photophysics of organic optoelectronic materials and nanodevices. In his group, they develop state-of-the-art ultrafast laser spectroscopy tools to observe and control molecular-scale dynamics in plastic solar cells, flexible transistors, quantum-dot photodetectors and other functional nanosystems. The prospective work includes charge-transport properties of proteins, ultrafast switching of organic transistors, and time-resolved spectroscopy on the scale of single molecules.

Details of the talk are below:

Soft electronic materials studied by ultrafast action spectroscopies with unusual probes - from vibrations to tunnelling electrons

"Soft" semiconductors, including organic molecular crystals and lead halide perovskites (LHP), are likely material candidates for the future cheap and efficient photovoltaic technologies. The heterogeneity of electronic properties and the interplay of structural and electronic dynamics in these systems play dominant role but are still poorly understood. In my talk, I will present two new spectroscopic techniques we have been developing to address the above issues.
First approach addresses the electron phonon coupling in LHP materials and rubrene molecular crystals using sequential vibrational + electronic 'VIPER' excitation of the sample with photocurrent and photoluminescence action detection. We demonstrate ultrafast vibrational control of FAPbBr3 perovskite solar cells via intramolecular vibrations of the A-site formamidinium cation. The study shows that molecular rotations modulating the couplings between cations and halides can suppress nonradiative recombination in perovskite materials, offering an important insight for the development of new photovoltaics with reduced voltage losses. We also apply the technique to molecular crystals observing that the crystal structure largely affects the coupling of different vibrational modes to the excitonic electronic states.
In the second approach, we aim to push action spectroscopies to the limit of observing dynamics in the individual nanosystems. For this we optically induce electron tunnelling across the metallic nanogaps containing nanosystems and use the produced electron pulses as a probe for electronic and structural dynamics.

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