Functional Energy Materials: From Fundamental Photophysics to Device Applications

The frontier in renewable energy applications lies in designing functional energy materials from molecular and nanostructured components as well as integrating these functional entities into optoelectronic devices. Fundamental insights into photophysics of each functional material and exquisite chemical control over the often disordered interfaces are essential to developing design strategies to optimize the energy flow across different functional entities in the device. The first part of this talk will focus on using ultrafast nonlinear spectroscopy with femtosecond temporal resolution to unravel several fundamentally interesting photophysical phenomena in functional energy materials, including quantum coherences in synthetic biomimetics and exciton relaxation in lead halide perovskite nanocrystals. The second part of the talk will focus on the design of solid-state NIR-to-visible upconversion devices that utilize bulk lead halide perovskites as triplet sensitizer and organic molecular materials as triplet–triplet annihilator to achieve optical conversion. Delicate control over the interfacial chemical composition and defects in these devices, in conjunction with surface characterization techniques, reveals that it is precisely the interfacial environment that both enables and limits the device performance.