title: High Performance All-Polymer Solar Cells by Synergistic Effects of Fine-Tuned Crystallinity and Solvent Annealing.
abstract: Growing interests have been devoted to the design of polymer acceptors as potential replacement for fullerene derivatives for high-performance all polymer solar cells (all-PSCs). One key factor that is limiting the efficiency of all-PSCs is the low fill factor (FF) (normally <0.65), which is strongly correlated with the mobility and film morphology of polymer:polymer blends. In this work, we find a facile method to modulate the crystallinity of the well-known naphthalene diimide (NDI) based polymer N2200, by replacing a certain amount of bithiophene (2T) units in the N2200 backbone by single thiophene (T) units and synthesizing a series of random polymers PNDI-Tx, where x is the percentage of the single T. The acceptor PNDI-T10 is properly miscible with the low band gap donor polymer PTB7-Th, and the nanostructured blend promotes efficient exciton dissociation and charge transport. Solvent annealing (SA) enables higher hole and electron mobilities, and further suppresses the bimolecular recombination. As expected, the PTB7-Th:PNDI-T10 solar cells attain a high PCE of 7.6%, which is a 2-fold increase compared to that of PTB7-Th:N2200 solar cells. The FF of 0.71 reaches the highest value among all-PSCs to date. Our work demonstrates a rational design for fine-tuned crystallinity of polymer acceptors, and reveals the high potential of all-PSCs through structure and morphology engineering of semicrystalline polymer:polymer blends.
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-412 96 Göteborg, Sweden.
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-412 96 Göteborg, Sweden.
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Xu
authors.affiliation: Division of Chemical Physics, Lund University , Box 124, 221 00 Lund, Sweden.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University , Xi'an 710049, China.
authors.forename: Xiangyi
authors.initials: X
authors.lastname: Meng
authors.affiliation: State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University , Xi'an 710049, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.affiliation: Division of Chemical Physics, Lund University , Box 124, 221 00 Lund, Sweden.
authors.forename: Arkady
authors.initials: A
authors.lastname: Yartsev
authors.affiliation: Biomolecular and Organic Electronics, IFM, Linköping University , SE-581 83 Linköping, Sweden.
authors.forename: Olle
authors.initials: O
authors.lastname: Inganäs
authors.affiliation: Future Industries Institute, University of South Australia , Mawson Lakes Boulevard, Mawson Lakes, SA 5095, Australia.
authors.forename: Mats R
authors.initials: MR
authors.lastname: Andersson
authors.affiliation: Molecular Materials and Nanosystems and Institute for Complex Molecular Systems, Eindhoven University of Technology , PO BOX 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: René A J
authors.initials: RA
authors.lastname: Janssen
authors.affiliation: Department of Chemistry and Chemical Engineering, Chalmers University of Technology , SE-412 96 Göteborg, Sweden.
authors.forename: Ergang
authors.initials: E
authors.lastname: Wang