Electronic Processes, Morphologies and Structural-functional Correlations in Conjugated Oligomers, Polymers and Perovskite for OPV/HOPV

Conjugated polymers with charge transfer characters in a large extend are responsible for the recent advancement in organic photovoltaic (OPV) applications in bulk heterojunction (BHJ) devices. Conventional organic photovoltaic models, in which donor molecules are treated as anonymous electron sources and charge carrier diffusion channels, are challenged by near-infrared transient absorption results of low bandgap polymers indicating strong correlations between intramolecular donor dynamics in < 100 fs and corresponding device power conversion efficiencies. The other conventional model being challenged is the driving force for exciton splitting in the bulk heterojunction environment which has been described by the LUMO-LUMO energy off-set between conjugated polymer electron donor and fullerene derivative electron acceptor. Our study suggests the intramolecular charge transfer characters must be combined with local and global conformations of conjugated polymer chains to achieve the low band gap.  Moreover, the morphology of the BHJ films is also investigated by in-situ GIWAS/GISAX methods including the effects of additives which suggest the interplays of the additives and the polymers in solution. More recent studies on structural evolution of perovskite film formation processes have been investigated using in-situ GIWAXS which enabled new and unexpected information to be revealed for controlling morphology of 2D perovskite materials.