Dark and Photovoltaic properties of p-CoPc/n-GaAs Heterojunction cells

Organic / inorganic heterojunction cells of p-CoPc/ n- GaAs, fabricated
by vacuum deposition of CoPc thin films onto GaAs single crystals, show a
conversion efficiency as high as 0.81% and an open circuit voltage of 0.33V
under illumination by light with a power density of 50 mWcm-2
. These
parameters have been estimated at room temperature. The estimated activation
energy of the charge carriers was found to be 0.35 eV and the cell series
resistance of 1kΩ. The above values have been evaluated from the
measurements of the dark I-V characteristics. The linearity of the C-2-V
dependence indicates that the junction is perfectly abrupt. From such
measurements the free-carrier concentration and the barrier width can be
estimated. Their values were found to be 1.2 x 1017 cm-3 and 32.4 nm,
respectively.