Complex morphologies and molecular ordering in OPVs: Critical parameters determined by soft x-ray scattering
Interface structure and the quantitative composition of morphology are known to be critical for fullerene based bulk heterojunction solar cells, yet have been very difficult to study previously due to a paucity of characterization methods. Recently developed soft X-ray microscopy and scattering tools provide new avenues and contribute substantially to indentify the number of phases present and to provide a quantitative measurement of their composition fluctuations and size distribution. This led to the realization that mixed domains are prevalent in OPVs and rather than just being detrimental can have important beneficial contributions for charge generation and charge transport. Furthermore, polarized x-ray scattering can reveal preferential orientation of the donor polymer (edge-on or face-on) relative to the fullerene aggregate interface. Such ordering has previously not been observed nor controlled in fullerene-based solar cells and is shown here to be a critical factor for high performance in a number of systems.
About Harald Ade
Dr. Ade holds appointments at NCSU since 1992 (Assist. Professor 1992-97, Assoc. Prof. 1997-2001, Prof. since 2001). He received his Ph.D. in 1990 in Physics from SUNY at Stony Brook and had joined the NCSU faculty in 1992. H. Ade received the K. F. J. Heinrich Award of the Microbeam Analysis Society (2000), a DuPont Young Faculty Award (1994-97) and an NSF Young Investigator Award (1994-1999). He was also recognized by a Sigma Xi Award of the NCSU Sigma Xi Chapter (1995) and an R&D100 Award (1990). He has delivered more than 200 invited presentations and (co)-authored over 155 research papers. He is a Fellow of the APS and AAAS and has an h-factor of 39 and a steeply raising citation rate.