Charge Transport in Photovoltaics

Above: Charge transport networks in strongly and weakly coupled molecular dyes.

(Fig. 1) The use of non-fullerene acceptors has exploded over the past decade, but there is still knowledge gaps on understanding how their packing can be optimized for both light absorption and electron transport. We are developing models to describe optimal charge transfer networks in different NFA molecular crystals.

The Schatz group has interest in describing the fundamental processes of light absorption and photoinduced energy/charge transfer dynamics in organic photovoltaic systems. These processes are modeled on different spatial and temporal length scales, and structural-property relationship is likewise built from the level of single molecules to supramolecular and mesoscale, and from the timescale of a few femtoseconds to several seconds. The materials of interest include non-fullerene acceptors (NFAs), donor-acceptor polymers, and molecular crystals.

The following projects highlight the current focus of the group.



(B)
(Fig. 2) Design considerations of NFA molecular crystals. (left) Fullerenes have low solubility but good pi-stacking interactions. (middle) First-generation NFAs such as perylene derivatives have strong slip-stacked interactions, but defects limit transport. (right) ITIC offers a high degree of tuning to optimize redundant transport networks and strong light absorption.






 











Leighton Jones, postdoctoral fellow

Recent Publications:

G Li, X Zhang, L O Jones, J M Alzola, S Mukherjee, L-w Feng, W Zhu, C L Stern, W Huang, J Yu, V K Sangwan, D M DeLongchamp, K L Kohlstedt, M R Wasielewski, M C Hersam, G C Schatz, A Facchetti, T J Marks. Systematic Merging of Nonfullerene Acceptor π-Extension and Tetrafluorination Strategies Affords Polymer Solar Cells with> 16% Efficiency. JACS 2021, 143, 6123-6139.

F Qi, L O Jones, K Jiang, S-H Jang, W Kaminsky, J Oh, H Zhang, Z Cai, C Yang, K L Kohlstedt, G C Schatz, F R Lin, T J Marks, A K-Y Jen Regiospecific N-alkyl substitution tunes the molecular packing of high-performance non-fullerene acceptors. Mat. Hor. 2021, Advanced Article.

S M Swick, T Gebraad, L Jones, B Fu, T J Aldrich, K L Kohlstedt, G C Schatz, A Facchetti, T J Marks. Building Blocks for High‐Efficiency Organic Photovoltaics: Interplay of Molecular, Crystal, and Electronic Properties in Post‐Fullerene ITIC Ensembles. Chem Phys Chem 2019, 20, 2608-2626.