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Improvement of photovoltaic response based on enhancement of spinorbital coupling and triplet states in organic solar cells

Journal Article · · Journal of Applied Physics
DOI:https://doi.org/10.1063/1.2885349· OSTI ID:1050935
 [1];  [1];  [2]
  1. University of Tennessee, Knoxville (UTK)
  2. ORNL
This article reports an improvement of photovoltaic response by dispersing phosphorescent Irppy3 molecules in an organic solar cell of poly2-methoxy-5-2-ethylhexyloxy-1 4-phenylenevinylene MEH-PPV blended with surface-functionalized fullerene 1-3-methyloxycarbonylpropy1-phenyl 6,6 C61 PCBM. The magnetic field dependent photocurrent indicates that the dispersed Irppy3 molecules increase the spin-orbital coupling strength with the consequence of changing the singlet and triplet ratios through intersystem crossing due to the penetration of the delocalized electrons of MEH-PPV into the large orbital magnetic field of Irppy3 dopants. The tuning of singlet and triplet exciton ratios can lead to an enhancement of photovoltaic response due to their different contributions to the two different photocurrent generation channels: exciton dissociation and exciton-charge reaction in organic materials. In addition, the photoluminescence temperature dependence reveals that the dispersed Irppy3 reduces the recombination of dissociated charge carriers in the PCBM doped MEH-PPV. As a result, adjusting singlet and triplet ratios by introducing heavy-metal complex Irppy3 provides a mechanism to improve the photovoltaic response through controlling exciton dissociation, exciton-charge reaction, and recombination of dissociated charge carriers in organic bulk-heterojunction solar cells.
Research Organization:
Oak Ridge National Laboratory (ORNL)
Sponsoring Organization:
SC USDOE - Office of Science (SC)
DOE Contract Number:
AC05-00OR22725
OSTI ID:
1050935
Journal Information:
Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 4 Vol. 103; ISSN JAPIAU; ISSN 0021-8979
Country of Publication:
United States
Language:
English