Research on Optical and Electrical Characteristics of Organic Photovoltaic Devices with Semitransparent Cathode
Date Issued
2009
Date
2009
Author(s)
Xu, Wei-Feng
Abstract
In this thesis, we demonstrated the organic photovoltaic (OPV) devices based on a copper phthalocyanine (CuPc) /fullerene (C60) /bathocuproine (BCP) hetero-junction structure with different thicknesses of Ag thin film as the semi-transparent cathode. The electrical and optical properties of the semi-transparent Ag films were discussed through the comparison of electrical conductivity and transparency. The electrical characteristics of the devices were compared under different side illuminated, from the anode side or the cathode side, respectively. By optimizing the thickness of metal contact (12.5 nm), we obtained the average transparency of ~32% over visible wavelength range and the power conversion efficiency (ηP) of 0.9% and 0.29% illuminated from the anode and cathode side, respectively. Moreover, the maximum transparency near 542 nm, which is sensitive to human eye, and ηP from top illumination can be increased up to 66.3% and 0.37%, respectively, by the introduction of organic capping layer (a-naphthylphenylbiphenyl diamine (NPB) = 40 nm) on top of thin cathode. In addition to the discussion of normal illumination, the effect of oblique and diffused light on the performance of semi-transparent OPV was also investigated. n the other hand, we tuned the thicknesses of organic layers in order to shift the maximum intensity in optical field distribution toward the dissociation interface between CuPc/C60, which increased the absorption probability of a photon entering the semi-transparent OPV. The device with optimized thickness of CuPc and C60 (20 nm/30 nm) reached the high ηP of 1.22 % illuminated from the anode side and 0.55% illuminated from the cathode side.
Subjects
Organic Photovoltaics (OPV)
Semitransparent Ag cathode
Transmittance
SDGs
Type
thesis
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