Resonance Chemical Imaging of Polythiophene/Fullerene Photovoltaic Thin Films: Mapping Morphology-Dependent Aggregated and Unaggregated C=C Species

被引:154
作者
Gao, Yongqian [1 ]
Grey, John K. [1 ]
机构
[1] Univ New Mexico, Dept Chem & Chem Biol, Albuquerque, NM 87131 USA
关键词
POLYMER/FULLERENE SOLAR-CELLS; INTERMOLECULAR INTERACTIONS; ORGANIC PHOTOVOLTAICS; CONFOCAL RAMAN; POLYMER; PERFORMANCE; EFFICIENCY; POLY(3-HEXYLTHIOPHENE); ABSORPTION; NETWORK;
D O I
10.1021/ja900636z
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Resonance Raman spectroscopic imaging is introduced as a physical probe to identify and spatially map morphology-dependent variations of intra- and interchain interactions and order in poly-3-hexylthiophene (P3HT) and [6,6]-phenyl-C-61-butyric acid methyl ester (PCBM) photovoltaic blend thin films. Absorption spectra and C=C symmetric stretching Raman modes of P3HT/PCBM blend films show contributions from two distinct species that are assigned as aggregated and unaggregated P3HT chains with characteristic Raman frequencies of similar to 1450 (I-C=C(agg)) and similar to 1470 cm(-1) (I-C=C(un)), respectively. Upon thermal annealing of blend films, the relative concentrations of I-C=C(agg) and I-C=C(un) species (R = I-C=C(agg)/I-C=C(un)) changes on average from 0.79 +/- 0.20 (as-cast) to 2.45 +/- 0.77 (annealed). It is proposed that R values report on the relative densities of states (DOS) of aggregated and unaggregated species, and resonance Raman imaging is then used to spatially map morphology-dependent variations of R values and uncover subclassifications of these species. From both Rand frequency dispersion resonance Raman images of I-C=C(agg) and I-C=C(un) species, four distinct types of P3HT chains are identified and mapped in annealed P3HT/PCBM blend thin films: (i) highly aggregated/crystalline, (ii) partially aggregated, (iii) interfacial, and (iv) unaggregated/PCBM rich. The change in aggregation upon annealing is attributed to an increase in planarity of the P3HT chains that is determined from the ratios of C=C/C-C symmetric stretching mode intensities.
引用
收藏
页码:9654 / 9662
页数:9
相关论文
共 50 条
[1]   Room to Improve Conjugated Polymer-Based Solar Cells: Understanding How Thermal Annealing Affects the Fullerene Component of a Bulk Heterojunction Photovoltaic Device [J].
Ayzner, Alexander L. ;
Wanger, Darcy D. ;
Tassone, Christopher J. ;
Tolbert, Sarah H. ;
Schwartz, Benjamin J. .
JOURNAL OF PHYSICAL CHEMISTRY C, 2008, 112 (48) :18711-18716
[2]   Ex and In Situ Confocal Raman Studies of Organic Thin Film and Its On-Working Transistors [J].
Bao, Qiaoliang ;
Gan, Ye ;
Li, Jun ;
Li, Chang Ming .
JOURNAL OF PHYSICAL CHEMISTRY C, 2008, 112 (49) :19718-19726
[3]   Effect of interchain interactions on the absorption and emission of poly(3-hexylthiophene) -: art. no. 064203 [J].
Brown, PJ ;
Thomas, DS ;
Köhler, A ;
Wilson, JS ;
Kim, JS ;
Ramsdale, CM ;
Sirringhaus, H ;
Friend, RH .
PHYSICAL REVIEW B, 2003, 67 (06)
[4]   Raman spectroscopy of intermolecular charge transfer complex between a conjugated polymer and an organic acceptor molecule [J].
Bruevich, V. V. ;
Makhmutov, T. Sh. ;
Elizarov, S. G. ;
Nechvolodova, E. M. ;
Paraschuk, D. Yu. .
JOURNAL OF CHEMICAL PHYSICS, 2007, 127 (10)
[5]  
Camaioni N, 2002, ADV MATER, V14, P1735, DOI 10.1002/1521-4095(20021203)14:23<1735::AID-ADMA1735>3.0.CO
[6]  
2-O
[7]   Morphology evolution via self-organization and lateral and vertical diffusion in polymer: fullerene solar cell blends [J].
Campoy-Quiles, Mariano ;
Ferenczi, Toby ;
Agostinelli, Tiziano ;
Etchegoin, Pablo G. ;
Kim, Youngkyoo ;
Anthopoulos, Thomas D. ;
Stavrinou, Paul N. ;
Bradley, Donal D. C. ;
Nelson, Jenny .
NATURE MATERIALS, 2008, 7 (02) :158-164
[8]   Infrared and Raman features of a series of α,ω-bis(arylthio)oligothiophenes as molecular wires.: A π-electron delocalization efficiency study [J].
Casado, J ;
Hicks, RG ;
Hernández, V ;
Myles, DJT ;
Delgado, MCR ;
Navarrete, JTL .
JOURNAL OF CHEMICAL PHYSICS, 2003, 118 (04) :1912-1920
[9]   Role of intermolecular coupling in the photophysics of disordered organic semiconductors: Aggregate emission in regioregular polythiophene [J].
Clark, Jenny ;
Silva, Carlos ;
Friend, Richard H. ;
Spano, Frank C. .
PHYSICAL REVIEW LETTERS, 2007, 98 (20)
[10]   Conjugated polymer photovoltaic cells [J].
Coakley, KM ;
McGehee, MD .
CHEMISTRY OF MATERIALS, 2004, 16 (23) :4533-4542