Research

We are using rheology to understand molecular interactions in semiconducting polymer solutions in order to guide the design of scalable solution-based processing methods of polymer based active layers for optoelectronic applications. We recently discovered a mechanism of cooling-induced viscoelastic phase separation to structure polymer nanocomposite solutions for solar cell applications. A combination of rheological measurements, temperature-dependent fluorescence microscopy and small angle neutron scattering are used to reveal the structure of the polymer gels.

We are using scaffolds to direct the solution-phase crystallization of small-molecule organic semiconductors into vertical crystal arrays optimized for maximum light absorption and charge transport. These scaffolds can dictate the size, location and orientation of crystals by controlling nucleation at the early stages of crystal growth. Our method is compatible with solution dip coating to continuously deposit vertical crystal arrays onto device platforms.

We are using nanoconfining scaffolds to shift the thermodynamics of polymorph phase transitions in metal-halide perovskites to improve their performance and stability for commercial solar energy harvesting applications. Using our generalizable strategy, we can suppress polymorph transitions to temperatures as low as 4 K and have reported unprecedented air stability of nanoconfined perovskite crystals against humidity-induced degradation.