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Title: Impact of interfacial molecular orientation on radiative recombination and charge generation efficiency

Here, a long standing question in organic electronics concerns the effects of molecular orientation at donor/acceptor heterojunctions. Given a well-controlled donor/acceptor bilayer system, we uncover the genuine effects of molecular orientation on charge generation and recombination. These effects are studied through the point of view of photovoltaics—however, the results have important implications on the operation of all optoelectronic devices with donor/acceptor interfaces, such as light emitting diodes and photodetectors. Our findings can be summarized by two points. First, devices with donor molecules face-on to the acceptor interface have a higher charge transfer state energy and less non-radiative recombination, resulting in larger open-circuit voltages and higher radiative efficiencies. Second, devices with donor molecules edge-on to the acceptor interface are more efficient at charge generation, attributed to smaller electronic coupling between the charge transfer states and the ground state, and lower activation energy for charge generation.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ; ORCiD logo [6] ;  [6] ;  [1] ;  [6] ;  [1] ; ORCiD logo [7] ;  [2] ;  [1]
  1. Univ. of California, Santa Barbara, CA (United States)
  2. Univ. of Potsdam, Potsdam (Germany)
  3. Univ. of California, Santa Barbara, CA (United States); Univ. of Potsdam, Potsdam (Germany)
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
  5. Univ. of California, Santa Barbara, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  6. Georgia Institute of Technology, Atlanta, GA (United States)
  7. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; electronic devices; solar cells
OSTI Identifier:
1374371