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The Roles of Poly(Ethylene Oxide) Electrode Buffers in Efficient Polymer Photovoltaics
Author(s) -
Jeng JunYuan,
Lin MingWei,
Hsu YaoJane,
Wen TenChin,
Guo TzungFang
Publication year - 2011
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201100314
Subject(s) - materials science , electrode , polymer solar cell , ethylene oxide , chemical engineering , oxide , polymer , work function , ethylene glycol , energy conversion efficiency , evaporation , metal , optoelectronics , copolymer , composite material , chemistry , thermodynamics , physics , engineering , metallurgy
The role of poly(ethylene oxide) polymer is investigated as an effective buffer with Al electrodes to markedly improve the electrode interface and enhance the open‐circuit voltage ( V OC ) and the power conversion efficiency ( PCE, η ) of poly(3‐hexylthiophene) (P3HT):[6,6]‐phenyl C61‐butyric acid methyl ester (PCBM)‐based bulk‐heterojunction ( BHJ ) solar cells. A unique process is developed by thermally co‐evaporating the poly(ethylene glycol) dimethyl ether (PEGDE, Mn ca. 2000) polymer with Al metal simultaneously at different ratios in vacuum (10 −6 Torr) to prepare the electrode buffers. The instant formation of a carbide‐like junction at the ethylene oxide/Al interface during the thermal evaporation is of essential importance to the extraction of electrons through the Al electrode. The performance of P3HT:PCBM‐based solar cells can be optimized by modulating the co‐evaporation ratios of the PEGDE polymer with Al metal due to the changes in the work functions of the electrodes. The V OC and η for devices fabricated with Al electrode are 0.44 V and 1.64%, respectively, and significantly improve to 0.58 V and 4.00% when applying the PEGDE:Al(2:1)/Al electrode. This research leads to a novel electrode design – free of salts, additives, complicated syntheses, and having tunable work function – for fabricating high‐performance photovoltaic cells.