Evaluation of internal potential distribution and carrier extraction properties of organic solar cells through Kelvin probe and time-of-flight measurements

Journal Article · Sun Sep 21 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4895712· OSTI ID:22306020

Tanaka, Yuya; Oda, Keisuke; Nakayama, Yasuo ^[1]; Noguchi, Yutaka; Ishii, Hisao ^[1]; Takahashi, Jun-ichi; Tokairin, Hiroshi ^[2]

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1. Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522 (Japan)
2. Advanced Technology Research Laboratories, Idemitsu Kosan Co., Ltd. Sodegaura 299-0293 (Japan)

The carrier extraction property of a prototypical small molecule organic solar cell (OSC) composed of copper phthalocyanine (CuPc), C⁶⁰, and bathocuproine (BCP) was studied on the basis of the internal potential distribution and carrier dynamics in the device. The internal potential distribution in the OSC structure at the interfaces and in the bulk region was determined by the Kelvin probe method. Significant potential gradients were found in the CuPc film on indium tin oxide and in the C⁶⁰ film on CuPc, consistent with charge transfer through the contacts. Moreover, surface potential of the BCP layer grew linearly with increasing film thickness with a slope of ca. 35 mV/nm (giant surface potential: GSP), which indicated spontaneous orientation polarization in the film. The potential gradient and GSP significantly changed the built-in potential of the device. Current–voltage and modified time-of-flight measurements revealed that the BCP layer worked as an electron injection and extraction layer despite the wide energy gap. These results were discussed based on the contributions of GSP and the gap states in the BCP layer.

• OSTI ID: 22306020
• Journal Information: Journal of Applied Physics, Vol. 116, Issue 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARRIERS
COPPER COMPLEXES
DISTRIBUTION
ELECTRIC POTENTIAL
ELECTRON BEAM INJECTION
ENERGY GAP
EVALUATION
EXTRACTION
FILMS
FULLERENES
INTERFACES
LAYERS
MOLECULES
ORGANIC SOLAR CELLS
PHTHALOCYANINES
POLARIZATION
SURFACE POTENTIAL
THICKNESS
TIME-OF-FLIGHT METHOD
TIN OXIDES