Executive Summary : | The study aims to reveal the ultrafast charge transfer dynamics controlling the efficiency of photofunctional materials in near-infrared (NIR) photodetectors. The Indian and German PIs will synthesize and characterize unsymmetrical squaraine (USQ) derivatives with donor-acceptor-donor D-A-D architectures, exhibiting high molar absorptivity and intense fluorescence in the near-infrared region. The femtosecond time-resolved optical and nanosecond time-resolved EPR spectra of these derivatives will be measured. The intermolecular interaction dynamics between USQ derivatives and PCBM will be investigated, and temperature-dependent time-resolved EPR spectra of USQ/PCBM complexes will be measured. The ideal chromophores will be applied in hybrid bulk heterojunction devices for detecting in the NIR range, and the efficiency of the photodetectors will be measured. The results of the ultrafast photophysical characterization and time-resolved EPR study will help elucidate the intermolecular charge transfer dynamics, identify new USQ sensitizers, benefit graduate and master students, and be published in high-impact international journals. If higher photoconversion efficiencies are obtained, the materials/concepts will be patented and collaborations with possible industrial partners will be pursued for commercialization. |