Superiority of branched side chains in spontaneous nanowire formation: Exemplified by poly(3-2-methylbutylthiophene) for high-performance solar cells
Journal
Small
Journal Volume
7
Journal Issue
8
Pages
1098-1107
Date Issued
2011
Author(s)
Chen, H. C.
Wu, I. C.
Hung, J. H.
Chen, F. J.
Chen, I. W. P.
Peng, Y. K.
Chen, C. H.
Tsao, H. K.
Abstract
One-dimensional nanostructures containing heterojunctions by conjugated polymers, such as nanowires, are expected to greatly facilitate efficient charge transfer in bulk-heterojunction (BHJ) solar cells. Thus, a combined theoretical and experimental approach is pursued to explore spontaneous nanowire formation. A dissipative particle dynamics simulation is first performed to study the morphologies formed by rodlike polymers with various side-chain structures. The results surprisingly predict that conjugated polymers with branched side chains are well suited to form thermodynamically stable nanowires. Proof of this concept is provided via the design and synthesis of a branched polymer of regioregular poly(3-2-methylbutylthiophene) (P3MBT), which successfully demonstrates highly dense nanowire formation free from any stringent conditions and stratagies. In BHJ solar cells fabricated using a blend of P3MBT and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM), P3MBT polymers are self-organized into highly crystalline nanowires with a d100 spacing of 13.30 Å. The hole mobility of the P3MBT:PC71BM (1:0.5 by weight) blend film reaches 3.83 A× 10-4 cm 2 V-1 s-1, and the maximum incident photon-to-current efficiency reaches 68%. The results unambiguously prove the spontaneous formation of nanowires using solution-processable conjugated polymers with branched alkyl side chains in BHJ solar cells. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Subjects
dissipative particle dynamics; nanowires; photovoltaic devices; solar cells
SDGs
Other Subjects
Alkyl side chains; Blend films; Branched Polymer; Branched side chains; Bulk heterojunction; Crystalline nanowires; Dissipative particle dynamics; Dissipative particle dynamics simulation; Experimental approaches; Highly dense; Incident photon-to-current efficiencies; Methyl esters; Nanowire formation; One-dimensional nanostructure; photovoltaic devices; Processable; Regio-regular; Rodlike polymer; Self-organized; Side chain structure; Spontaneous formation; Thermodynamically stable; Butyric acid; Charge transfer; Esters; Heterojunctions; Hole mobility; Ion exchange; Nanowires; Photovoltaic effects; Solar cells; Solar power generation; Conjugated polymers; nanowire; polymer; thiophene derivative; absorption; article; atomic force microscopy; chemistry; electricity; solar energy; spectroscopy; thermodynamics; ultrastructure; X ray diffraction; Absorption; Electricity; Microscopy, Atomic Force; Nanowires; Polymers; Solar Energy; Spectrum Analysis; Thermodynamics; Thiophenes; X-Ray Diffraction
Type
journal article