Effect of growth rate on exciton generation and charge transport in polymer/fullerene bulk heterojunctions

PMSE 252

Vishal Shrotriya, vshro@seas.ucla.edu1, Yan Yao, yanyao05@gmail.com2, Gang Li1, and Yang Yang, yangy@ucla.edu1. (1) Department of Materials Science and Engineering, UCLA, Los Angeles, CA 90095, (2) Department of Materials Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095
We have investigated the effect of self-organization on the performance of polymer bulk heterojunction solar cells. The higher degree of ordering in the active layer, which is achieved by controlling the growth rate of the active layer, results in an enhanced device performance. The effect of growth rate on the morphology of the active layer is studied by atomic force microscopy technique. The electrical characterization by dark current and photocurrent measurements is performed. The hole mobility in the polymer increases by about two orders in magnitude and the carrier transport becomes highly balanced. At the short-circuit condition, the electron-hole pair dissociation efficiency is more than 80%, which is the highest value observed for polymer bulk-heterojunction. A high efficiency of electron-hole pair dissociation, coupled with an increased exciton generation rate, higher carrier mobilities and balanced carrier transport in the donor-acceptor blend film, explain the observed enhancement in the short-circuit current and fill factor.
 

Joint PMSE/POLY Poster Session
6:00 PM-8:00 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster

Division of Polymeric Materials: Science & Engineering

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006