| Abstract [eng] |
This master’s thesis investigates charge carrier transport properties in organic mixed semiconductor layers intended for potential application in X-ray detectors. The study focuses on newly synthesized boron-containing small molecules V1681, V1770, and V1822, as well as commercially available o- and m-carboranes. These materials were blended with the polymer PEPK and additional charge-transport materials, TPD and K-160, in order to improve film formation, morphological stability, and charge transport properties. Charge carrier mobilities were investigated using the time-of-flight method, while the thicknesses of the prepared layers were determined by the CELIV technique. The results showed that pure boron-containing materials often suffer from poor solubility or crystallization, which makes the formation of homogeneous layers difficult. However, blending these materials with PEPK and charge-transport compounds improved the film morphology and enabled the measurement of both electron and hole transport. The highest electron and hole mobilities were obtained in V1681-based mixtures, reaching approximately 3.5·10⁻⁵ cm²·V⁻¹·s⁻¹. V1770-based mixtures showed lower carrier mobilities but better film-forming properties and lower dark current, which resulted in a favorable irradiated-to-dark current ratio in detector-type measurements. V1822-based mixtures produced the strongest X-ray-induced photocurrent and therefore showed the highest potential for further development of organic X-ray detectors. Nevertheless, further optimization of layer fabrication and electrode materials is required to reduce dark current and improve the reproducibility of the devices. |
