skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Direct determination of the electronic structure of the poly(3-hexylthiophene):phenyl-[6,6]-C61 butyric acid methyl ester blend

Journal Article · · Org. Electron.
 [1];  [1];  [1];  [2];  [2];  [1];  [1]
  1. Princeton Univ., NJ (United States)
  2. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)

This article focuses on the electronic structure of the poly(3-hexylthiophene):phenyl-[6,6]-C61 butyric acid methyl ester (P3HT:PCBM) blend, widely used in bulk heterojunction (BHJ) solar cells. Given the fact that the surface of the blend film is a nearly pure P3HT wetting layer, we use a lift-off method to access the originally buried surface, which is rich in both P3HT and PCBM and thus representative of the BHJ. The combination of direct and inverse photoemission spectroscopy on this surface leads to a determination of the energy gap between the lowest unoccupied molecular orbital (LUMO) of the acceptor and the highest occupied molecular orbital (HOMO) of the donor. The gap is ~1.4 eV, which implies a 0.5–0.6 eV interface dipole barrier between the two materials. The energy gap is found to be stable versus in situ annealing up to 100 °C.

Research Organization:
Energy Frontier Research Centers (EFRC) (United States). Center for Interface Science: Solar Electric Materials (CISSEM)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
DOE Contract Number:
SC0001084
OSTI ID:
1064773
Journal Information:
Org. Electron., Vol. 11, Issue 11; Related Information: CISSEM partners with the University of Arizona (lead); Georgia Institute of Technology; National Renewable Energy Laboratory; Princeton University; University of Washington
Country of Publication:
United States
Language:
English