My research focuses on developing energy-efficient multifunctional sensors via the use of novel semiconductor device architectures. We have developed dye sensitized photovoltaic systems that can detect common contaminants in drinking water such as silver ions, while powering their own operation by converting absorbed ambient light into an electrical signal. We have also successfully fabricated an efficient single pixel organic light emitting device that generates changes in electrical current upon touch, a system that may have interesting implications for the next generation of touchscreens. Currently, I am working on integrating nanophotonic light concentrator structures with organic photodetectors for low-power sensors that leverage traditional high-sensitivity optical schemes such as those based on chemiluminescence of certain dyes in the presence of heavy metal ions.
My research focuses on breaking the tradeoff between absorption and exciton diffusion in organic photovoltaics using novel device design. By employing cascade heterojunction (CHJ) device structures, we have broadened spectral response and minimized parasitic recombination of excitons at the anode and in the bulk of planar OPVs. We've also developed a predictive model for determining the external quantum efficiency of CHJs and established practical design rules to ensure high fill factor and IQE in those structures. We are currently investigating long-range resonant energy transfer in CHJs to further increase device absorption (across the visible spectrum and at absorption peaks) without limiting exciton diffusion efficiency.
My research involves using origami and kirigami design principles to develop novel devices for a wide range of photovoltaic and other optoelectronic applications. Currently, we are investigating the combination of thin film solar cells and tunable kirigami structures as a lightweight, compact, and economical alternative to conventional solar tracking. These devices consist of a simple kirigami cut pattern integrated with thin-film solar cells, whereby pulling on the structure in the axial direction results in a global and predictable change in solar cell angle (Figure 1). By leveraging the unique geometric properties of the kirigami substrate itself, and the excellent electrical and mechanical properties of thin film solar cells, we have demonstrated an efficient and robust tracking method that we hope will significantly broaden the use of solar tracking to new market segments such as mobile and residential (pitched) rooftop tracking
My research focuses on Organic Vapor Jet Printing (OVJP) of small molecular materials. This deposition technique enables solvent- and vacuum-free patterning of small molecular compounds on any substrate and any shape. Using OVJP we are able to access a unique surface morphologies in organic films with many promising applications, such as semiconductors, pharmaceuticals and food industries. Currently, I am working to develop models that predict the morphology of organic films grown by OVJP, evaluate thermophysical properties of small molecular compounds, optimize patterning resolution of small organic molecules used in organic semiconductor industry (organic light emitting diodes, organic this film transistors and organic photovoltaics). I’m also developing novel processing techniques for improvement of bioavailability of small molecular pharmaceuticals with poor aqueous solubility.
My research focuses on strongly bound electron-hole pairs (excitons) that are generated during the absorption/emission process in organic materials, and their coupling to optical modes inside ultrathin organic photovoltaics (OPVs) and organic light-emitting diodes (OLEDs). Through hybridization with surface plasmon polaritons in thin metal cavities or by tuning their interaction with neighboring media, it is possible to modify exciton formation, recombination, and diffusion dynamics. I employ both experiments and classical electromagnetic theory to study the effects such near-field interactions have on device performance. By controlling optical interactions, I seek to break some of the fundamental tradeoffs intrinsic to organic optoelectronic devices.