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Title: Molecular engineering to improve carrier lifetimes for organic photovoltaic devices with thick active layers

Journal Article · · Organic Electronics
ORCiD logo [1];  [1];  [1];  [2];  [3];  [1];  [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Univ. of Santa Cruz, Santa Cruz, CA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
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The morphology of the bulk heterojunction absorber layer in an organic photovoltaic (OPV) device has a profound effect on the electrical properties and efficiency of the device. Previous work has consistently demonstrated that the solubilizing side-chains of the donor material affect these properties and device performance in a non-trivial way. Here, using Time-Resolved Microwave Conductivity (TRMC), we show by direct measurements of carrier lifetimes that the choice of side chains can also make a substantial difference in photocarrier dynamics. We have previously demonstrated a correlation between peak photoconductance measured by TRMC and device efficiencies; here, we demonstrate that TRMC photocarrier dynamics have an important bearing on device performance in a case study of devices made from donor materials with linear vs. branched side-chains and with variable active layer thicknesses. We use Grazing-Incidence Wide Angle X-ray Scattering to elucidate the cause of the different carrier lifetimes as a function of different aggregation behavior in the polymers. Consequently, the results help establish TRMC as a technique for screening OPV donor materials whose devices maintain performance in thick active layers (>250 nm) designed to improve light harvesting, film reproducibility, and ease of processing.

Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Grant/Contract Number:
AC36-08GO28308; AC36-08-GO28038; AC02-76SF00515; AC36-08GO28038
OSTI ID:
1357949
Alternate ID(s):
OSTI ID: 1374535; OSTI ID: 1396380
Report Number(s):
NREL/JA-5900-68309
Journal Information:
Organic Electronics, Vol. 47, Issue C; ISSN 1566-1199
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 6 works
Citation information provided by
Web of Science

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Related Subjects

14 SOLAR ENERGY
42 ENGINEERING
time-resolved microwave conductivity
organic photovoltaics
x-ray diffraction
carrier lifetime
layer thickness