Design, Synthesis And Applications Of Novel Molecules For Light-Controlled Carrier Switch

The photochromic diarylethene compounds based on perfluoro-cyclopentene have outstanding thermal stability and fatigue resistant property. There are distinct photochemical properties between their open-ring forms and closed-ring forms, which makes them as potential candidates for optical devices such as optical memories and switches.As one of organic semiconductors, the conjugated extents of pi-electrons between the two photo-isomers of diarylethene compounds are much different, and their ionization potentials (Ip), also the energy levels of the highest occupied molecular orbital (HOMO), are much different accordingly. The value of this difference (ΔIp) is usually about 0.6 eV. To obtain higher Ip change (ΔIp) between the open-ring form and closed-ring form, ferrocene was introduced into the diarylethene compounds, which had changed the extent of conjugated effect in the target molecules. As a result, a novel diarylethene molecule (DAE-12) with higher value ofΔIp, 0.8 eV, was successfully obtained. Finally, a smart light-controlled carrier switch in an organic light emitting device based on the DAE-12 had been prepared, and a real ON-OFF carrier switch was obtained successfully.To obtain a real ON-OFF carrier in the design of light-controlled carrier switch with block layer style, two commands have to be met. firstly, the diarylethens used as block layer of light-controlled carrier switch must have large enough value ofΔIp, and then in one state the transporting of carrier is favored or is blocked in another state. Secondly, the energy levels of every layer in a designed device have to be matched each other.Quantum chemical calculations were carried out in order to investigate the photoelectric performance of our target molecules. According to the results of our quantum chemical calculations, the HOMOs are usually distributed along the thiophene-perfluorocyclopentene-thiophene skeleton of diarylethene molecule in both of the open-ring state and closed-ring state. Under this condition, the changes of HOMO distribution are relatively small, which shows the reason why values ofΔIp are usually 0.6 eV for most of diarylethene compounds. However, as far as the DAE-12 is concerned, the HOMO is distributed on its different conjugated system. The results of quantum chemical calculations would be a guidance for design, synthesis of novel molecules used in light-controlled carrier switches.