Near-Infrared Organic Semiconductor Materials for Optoelectronic Technologies

The current success of organic semiconductor technology is mainly driven by the development of organic light-emitting diodes (OLED), which are now routinely employed in display technologies. In the last decade, however, organic photovoltaics (OPV), leveraging the impressive improvement in device efficiency and stability, have gradually moved from a lab curiosity to a niche market. Their recent success has coincided with the rapid development of organic semiconductor materials, both electron donors and electron acceptors, with absorption covering the UV-Vis-NIR part of the light spectrum.1 Through strategic design adopting different chemical building blocks, these new materials afforded high absorption with tuneable energetics into the NIR region of the electromagnetic spectrum. This allowed the development of NIR organic photodetector (OPD), novel photoacoustic probes for bioimaging applications, and more recently enabled the development of quinoidal conjugated polymers with open-shell character with distinctive opto-electronic and magnetic properties.2,3 This synergistic project will build on the expertise of the Schroeder group at UCL in the synthesis of low bandgap organic semiconductors and the know-how of the Gasparini group at ICL in the fabrication and characterisation of high efficiency NIR OPD devices. The project will focus on the design and synthesis of the next generation of NIR absorbing organic semiconductors with an absorption band extending deep into the NIR (~ 1600 nm) and their initial incorporation into OPD devices for NIR photodetection. The aim of this project is (i) to develop and synthesise novel NIR absorbing organic semiconductors and (ii) to obtain OPD with photodetection in the NIR region and low dark current (Jd). The chemical design of organic semiconductors with relatively narrow and specific absorption spectra will allow OPDs to be explored for selective narrowband NIR photodetection, where effective-material choices for biomedical applications and process monitoring remain scarce.