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Improved Performance of Polymer:Polymer Solar Cells by Doping Electron‐Accepting Polymers with an Organosulfonic Acid
Author(s) -
Nam Sungho,
Shin Minjung,
Kim Hwajeong,
Ha ChangSik,
Ree Moonhor,
Kim Youngkyoo
Publication year - 2011
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201101215
Subject(s) - materials science , doping , x ray photoelectron spectroscopy , polymer , photoluminescence , polymer solar cell , chemical engineering , quenching (fluorescence) , energy conversion efficiency , open circuit voltage , analytical chemistry (journal) , optoelectronics , voltage , composite material , organic chemistry , optics , fluorescence , chemistry , physics , quantum mechanics , engineering
The performance of polymer:polymer solar cells that are made using blend films of poly(3‐hexylthiophene) (P3HT) and poly(9,9‐dioctylfluorene‐co‐ benzothiadiazole (F8BT) is improved by doping the F8BT polymer with an organosulfonic acid [4‐ethylbezenesulfonic acid (EBSA)]. The EBSA doping of F8BT, to form F8BT‐EBSA, is performed by means of a two‐stage reaction at room temperature and 60°C with various EBSA weight ratios. The X‐ray photoelectron spectroscopy measurement reveals that both sulfur and nitrogen atoms in the F8BT polymer are affected by the EBSA doping. The F8BT‐EBSA films exhibit huge photoluminescence quenching, ionization potential shift toward lower energy, and greatly enhanced electron mobility. The short‐circuit current density of solar cells is improved by ca. twofold (10 wt.% EBSA doping), while the open‐circuit voltage increases by ca. 0.4 V. Consequently, the power conversion efficiency was improved by ca. threefold, even though the optical density of the P3HT:F8BT‐EBSA blend film is reduced by 10 wt.% EBSA doping due to the nanostructure and surface morphology change.