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Title: Tuning domain size and crystallinity in isoindigo/PCBM organic solar cells via solution shearing

Journal Article · · Organic Electronics
ORCiD logo [1];  [1];  [2];  [2];  [3];  [1];  [4];  [5]; ORCiD logo [1]
  1. Stanford Univ., Stanford, CA (United States)
  2. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  3. Univ. of Illinois at Urbana-Champaign, Urbana, IL (United States)
  4. Iowa State Univ., Ames, IA (United States)
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States)

Despite having achieved the long sought-after performance of 10% power conversion efficiency, high performance organic photovoltaics (OPVs) are still mostly constrained to lab scale devices fabricated by spin coating. Efforts to produce printed OPVs lag considerably behind, and the sensitivity to different fabrication methods highlights the need to develop a comprehensive understanding of the processing-morphology relationship in printing methods. Here we present a systematic experimental investigation of a model low bandgap polymer/fullerene system, poly-isoindigo thienothiophene/PC61BM, using a lab-scale analogue to roll-to-roll coating as the fabrication tool in order to understand the impact of processing parameters on morphological evolution. We report that domain size and polymer crystallinity can be tuned by a factor of two by controlling the temperature and coating speed. Lower fabrication temperature simultaneously decreased the phase separation domain size and increased the relative degree of crystallinity in those domains, leading to improved photocurrent. We conclude that domain size in isoindigo/PCBM is dictated by spontaneous phase separation rather than crystal nucleation and growth. Moreover we present a model to describe the temperature dependence of domain size formation in our system, which demonstrates that morphology is not necessarily strictly dependent on the evaporation rate, but rather on the interplay between evaporation and diffusion during the printing process.

Research Organization:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
Grant/Contract Number:
N00014-14-1-0142; 1434799; 1435587; 1149365; AC02-05CH11231; AC02-76SF00515
OSTI ID:
1361161
Alternate ID(s):
OSTI ID: 1398694
Journal Information:
Organic Electronics, Vol. 40, Issue C; ISSN 1566-1199
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 16 works
Citation information provided by
Web of Science

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Cited By (5)

Surpassing 10% Efficiency Benchmark for Nonfullerene Organic Solar Cells by Scalable Coating in Air from Single Nonhalogenated Solvent journal January 2018
Modeling of Actual-Size Organic Electronic Devices from Efficient Molecular-Scale Simulations journal May 2018
Side-chain engineering in a thermal precursor approach for efficient photocurrent generation journal January 2017
The meniscus-guided deposition of semiconducting polymers journal February 2018
Surpassing 10% Efficiency Benchmark for Nonfullerene Organic Solar Cells by Scalable Coating in Air from Single Nonhalogenated Solvent text January 2018