Kai Yao

Efficient all polymer solar cells from layer-evolved processing of a bilayer inverted structure

A new electron acceptor poly(indacenodiselenophene-difluorobenzothiadiazole) was used to fabricate bilayer all-polymer solar cells with a high power conversion efficiency (2.5%). By using the layer-evolved bilayer structure with interfacial modification, it alleviates unbalanced charge carrier mobility and reduces bimolecular recombination within the BHJ device.

Performance limits of plasmon-enhanced organic photovoltaics

We use a combination of experiment and modeling to explore the promise and limitations of using plasmon-resonant metal nanoparticles to enhance the device performance of organic photovoltaics (OPVs). We focus on optical properties typical of the current generation of low-bandgap donor polymers blended with the fullerene (6,6)-phenyl C71-butyric acid methyl ester (PC71BM) and use the polymer poly(indacenodithiophene-co-phenanthro[9,10-b]quinoxaline) (PIDT-PhanQ) as our test case. We model the optical properties and performance of these devices both in the presence and absence of a variety of colloidal silver nanoparticles. We show that for these materials, device performance is sensitive to the relative z-position and the density of nanoparticles inside the active layer. Using conservative estimates of the internal quantum efficiency for the PIDT-PhanQ/PC71BM blend, we calculate that optimally placed silver nanoparticles could yield an enhancement in short-circuit current density of over 31% when used with...