TY - JOUR
T1 - Harnessing Structure-Property Relationshipsfor Poly(alkyl thiophene)-Fullerene Derivative Thin Filmsto Optimize Performance in Photovoltaic Devices
AU - Deb, Nabankur
AU - Li, Bohao
AU - Skoda, Maximilian
AU - Rogers, Sarah
AU - Sun, Yan
AU - Gong, Xiong
AU - Karim, Alamgir
AU - Sumpter, Bobby G.
AU - Bucknall, David G.
N1 - Publisher Copyright:
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
PY - 2016/3/22
Y1 - 2016/3/22
N2 - Nanoscale bulk heterojunction (BHJ) systems, consisting of fullerenes dispersed in conjugated polymers have been actively studied in order to produce high performance organic photovoltaics. How the BHJ morphology affects device efficiency, is currently ill-understood. Neutron reflection together with grazing incidence X-ray and neutron scattering and X-ray photoelectron spectroscopy are utilized to gain understanding of the BHJ morphology in functional devices. For nine model systems, based on mixtures of three poly(3-alkyl thiophenes, P3AT) (A = butyl, hexyl, octyl) blended with three different fullerene derivatives, the BHJ morphology through the film thickness is determined. It is shown that fullerene enrichment occurs at both the electrode interfaces after annealing. The degree of fullerene enrichment is found to strongly correlate with the short circuit current (JSC) and to a lesser degree with the fill factor. Based on these findings, it is demonstrated that by deliberately adding a fullerene layer at the electron transport layer interface, JSC can be increased by up to 20%, resulting in an overall increase in power conversion efficiency of 5%.
AB - Nanoscale bulk heterojunction (BHJ) systems, consisting of fullerenes dispersed in conjugated polymers have been actively studied in order to produce high performance organic photovoltaics. How the BHJ morphology affects device efficiency, is currently ill-understood. Neutron reflection together with grazing incidence X-ray and neutron scattering and X-ray photoelectron spectroscopy are utilized to gain understanding of the BHJ morphology in functional devices. For nine model systems, based on mixtures of three poly(3-alkyl thiophenes, P3AT) (A = butyl, hexyl, octyl) blended with three different fullerene derivatives, the BHJ morphology through the film thickness is determined. It is shown that fullerene enrichment occurs at both the electrode interfaces after annealing. The degree of fullerene enrichment is found to strongly correlate with the short circuit current (JSC) and to a lesser degree with the fill factor. Based on these findings, it is demonstrated that by deliberately adding a fullerene layer at the electron transport layer interface, JSC can be increased by up to 20%, resulting in an overall increase in power conversion efficiency of 5%.
KW - bulk heterojunctions
KW - fullerenes
KW - morphology
KW - organic photovoltaics
KW - polyalkylthiophenes
UR - http://www.scopus.com/inward/record.url?scp=84969335471&partnerID=8YFLogxK
U2 - 10.1002/adfm.201502653
DO - 10.1002/adfm.201502653
M3 - Article
AN - SCOPUS:84969335471
SN - 1616-301X
VL - 26
SP - 1908
EP - 1920
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 12
ER -