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High‐Efficiency Organic Solar Cells Based on Preformed Poly(3‐hexylthiophene) Nanowires
Author(s) -
Kim Jong Soo,
Lee Ji Hwang,
Park Jong Hwan,
Shim Chiyeoung,
Sim Myungsun,
Cho Kilwon
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.201000971
Subject(s) - materials science , nanowire , energy conversion efficiency , polymer solar cell , heterojunction , charge carrier , optoelectronics , electron mobility , chemical engineering , electrode , hybrid solar cell , indium , active layer , nanotechnology , layer (electronics) , chemistry , engineering , thin film transistor
Bulk heterojunction solar cells based on blends of poly(3‐hexylthiophene) (P3HT) and phenyl‐C61‐butyric acid methyl ester (PC 61 BM) are fabricated using self‐assembled P3HT nanowires in a marginal solvent without post‐treatments. The interconnected network structures of self‐organized P3HT nanowires create continuous percolation pathways through the active layer and contribute to enhanced carrier mobility. The morphology and photovoltaic properties are studied as a function of ageing time of the P3HT precursor solution. Optimal photovoltaic properties are found at 60 h ageing time, which increases both light absorption and charge balance. Multilayered solar cells with a compositionally graded structure are fabriacted using preformed P3HT nanowires by inserting a pure P3HT donor phase onto the hole‐collecting electrode. Applying optimized annealing conditions to the P3HT buffer layer achieves an enhanced hole mobility and a power conversion efficiency of 3.94%. The introduction of a compositionally graded device structure, which contains a P3HT‐only region, reduces charge recombination and electron injection to the indium tin oxide (ITO) electrode and enhances the device properties. These results demonstrate that preformed semiconductor nanowires and compositionally graded structures constitute a promising approach to the control of bulk heterojunction morphology and charge‐carrier mobility.