The general theme of my research is based on the analysis of π-conjugated organic compounds as modern electrically conductive materials for application in organic electronics. During my work, I have been conducting research in several areas concerning processes occurring in organic electronic devices. This research has involved comprehensive studies in different scientific areas, across various scientific disciplines. My main expertise is the electrochemical and spectroelectrochemical analysis of organic compounds. Specifically, I’m using electrochemical methods in the studies of doping mechanisms of conjugated compounds to estimate the ionization potential (IP) and electron affinity (EA), which are correlated with HOMO and LUMO energy levels. Additional electrochemical measurements allowed me to investigate the possible side reactions during the degradation of the active layer and the formation of low mobility charge carriers (bipolarons). Coupling electrochemical and spectroelectrochemical methods additionally helped me to accurately and reliably determine features such as the degree of oxidation or reduction of the conjugated compound and degradation potential, which is crucial for assessing the stability of a material upon doping. I also apply visible light and near-infrared spectroscopy coupled with electrochemistry to characterize the fundamentals of the chromatic properties of several conjugated compounds. For this purpose, I use an Electron Paramagnetic Resonance (EPR) spectrometer coupled with a potentiostat. Bearing in mind that in this process two classes of charged quasiparticles take part, one endowed with uncompensated spin (polarons) and the second being diamagnetic (bipolarons), EPR spectroscopy allowed me for direct observation of populations of paramagnetic polarons and to track their changes. I have been also using IR spectroscopy and Raman spectroscopy as the basic tools providing complementary information on the types of chemical bonds present in the chemicals being analyzed.
My current work is mainly devoted to the application of organic compounds as TADF (thermally activated delayed fluorescence) and RTP (room temperature phosphorescence) emitters, from molecular design through to working devices. As the standard practice of my work, I’m designing and screening new materials (in both solution and solid state) for photoluminescence quantum yield (PLQY), fluorescence and phosphorescence emission output, and absorption, in a range of polar and nonpolar solvents, in order to identify the solvatochromism of any CT state. In order to distinguish between different excitation states and the fluorescence and phosphorescence processes, I’m using a gated iCCD camera with a laser excitation system, which allows me to measure emission at different time delays. Using TCSPC (Time-Correlated Single Photon Counting) and iCCD photoluminescence measuring systems, I’m able to obtain the delayed emission (both TADF, TTA – Triplet-Triplet Annihilation and RTP – Room Temperature Phosphorescence) decay time profile and compare the prompt fluorescence and the delayed emission at different temperatures. During my work, I also use impedance spectroscopy for studying relaxation and transport in various electronic devices based on organic materials. All of the gained data in electrochemical and spectroscopic analysis allow me to predict ideal OLED device structures and optimize working parameters. In the final stage of my research, the OLED devices are formed and analysed.
My recent projects cover mainly the designing and analysis of organic compound for Organic Electronics applications like OLED, OPV and OFET, but also electrochromic windows and organic Peltier elements.