title: Effect of polymer aggregation on the open circuit voltage in organic photovoltaic cells: aggregation-induced conjugated polymer gel and its application for preventing open circuit voltage drop.
abstract: To investigate the structure-dependent aggregation behavior of conjugated polymers and the effect of aggregation on the device performance of conjugated polymer photovoltaic cells, new conjugated polymers (PVTT and CN-PVTT) having the same regioregularity but different intermolecular packing were prepared and characterized by means of UV-vis spectroscopy and atomic force microscopy (AFM). Photovoltaic devices were prepared with these polymers under different polymer-aggregate conditions. Polymer aggregation induced by thermal annealing increases the short circuit current but provides no advantage in the overall power conversion efficiency because of a decrease in the open circuit voltage. The device fabricated from a pre-aggregated polymer suspension, acquired from ultrasonic agitation of a conjugated polymer gel, showed enhanced performance because of better phase separation and reduced recombination between polymer/PCBM.
authors.affiliation: Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States.
authors.forename: Bong-Gi
authors.initials: BG
authors.lastname: Kim
authors.forename: Eun Jeong
authors.initials: EJ
authors.lastname: Jeong
authors.forename: Hui Joon
authors.initials: HJ
authors.lastname: Park
authors.forename: David
authors.initials: D
authors.lastname: Bilby
authors.forename: L Jay
authors.initials: LJ
authors.lastname: Guo
authors.forename: Jinsang
authors.initials: J
authors.lastname: Kim
mesh_terms: D017097:Electric Impedance; D011211:Electric Power Supplies; D004574:Electromagnetic Fields; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005782:Gels / Q000737:chemistry; D008027:Light; D009930:Organic Chemicals / Q000737:chemistry*; D010777:Photochemistry / Q000295:instrumentation*; D011108:Polymers / Q000737:chemistry*; D013010:Sonication
chemical_list: D005782:Gels; D009930:Organic Chemicals; D011108:Polymers