Journal
ACS NANO
Volume 5, Issue 8, Pages 6233-6243Publisher
AMER CHEMICAL SOC
DOI: 10.1021/nn2010816
Keywords
GISAXS; GIWAXS; structural kinetics; bulk heterojunction solar cells; charge mobility
Categories
Funding
- National Science Council [NSC 99-2112-M-213-002-MY3]
Ask authors/readers for more resources
Concomitant development of [6,6]-phen-C-61-butyric acid methyl ester (PCBM) aggregation and poly(3-hexylthiophene) (P3HT) crystallization in bulk heterojunction (BHJ) thin-film (ca. 85 nm) solar cells has been revealed using simultaneous grazing incidence small-/wide-angle X-ray scattering (GISAXS/GIWAXS). With enhanced time and spatial resolutions (5 s/frame; minimum q approximate to 0.004 angstrom(-1)), synchrotron GISAXS has captured In detail the fast growth in size of PCBM aggregates from 7 to 18 nm within 100 s of annealing at 150 degrees C. Simultaneously observed is the enhanced crystallization of P3HT Into lamellae oriented mainly perpendicular but also parallel to the substrate. An Avrami analysis of the observed structural evolution indicates that the faster PCBM aggregation follows a diffusion-controlled growth process (confined by P3HT segmental motion), whereas-the slower development of crystalline P3HT nanograins is characterized by constant nucleation rate (determined by the degree. of supercooling and POW demixing). These two competing kinetics result in local phase separation with space filling PCBM and P3HT nanodomains less than 20 nm in size when annealing temperature is kept below 180 degrees C. Accompanying the morphological development is the synchronized Increase In electron and hole mobilities of the BHJ thin-film solar cells, revealing the sensitivity of the carrier transport of the device on the structural features of PCBM and P3HT nanodomains. Optimized structural parameters, including the aggregate size and mean spacing of the PCBM aggregates, are quantitatively correlated to the device performance; a comprehensive network structure of the optimized BHJ thin film is presented.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available