Thermal annealing induced bicontinuous networks in bulk heterojunction solar cells and bipolar field-effect transistors

Abstract

Polymer bulk heterojunction solar cells fabricated from poly (2,5-bis(3'-dodecyl-2,2'-bithiophen-5-yl)-3,6-dimethylthieno [3,2-b] thiophene):[6,6]-phenyl-C(61)-butric acid methyl ester (1:1, w/w (blend showed significantly improved power conversion efficiency (PCE), from 0.96% to 2.32%, with post-thermal annealing at 140 degrees C. Charge transport properties obtained from bipolar field-effect transistors indicated that post-thermal annealing induced the assembly of significantly improved bicontinuous networks and excellently balanced hole (7.2 x 10(-3) cm(2) V(-1) s(-1)) and electron (5.8 x 10(-3) cm(2) V(-1) s(-1)) mobilities (due, particularly, to improved electron mobility), thereby improving PCE. (C) 2009 American Institute of Physics. [doi:10.1063/1.3254234]