Gd. Sharma, ELECTRICAL AND PHOTOELECTRICAL PROPERTIES OF SCHOTTKY-BARRIER DEVICESUSING THE CHLORO ALUMINUM PHTHALOCYANINES, Synthetic metals, 74(3), 1995, pp. 227-234
Measurements of electrical and photoelectrical properties of Al/ClAlPc
/ITO, In/ClAlPc/ITO and Au/ClAlPc/Au are presented. The devices Al/ClA
lPc/ITO and In/ClAlPc/ITO show rectification properties, while device
Au/ClAlPd/Au does not show rectification properties. These effects are
explained in terms of p-type semiconducting behaviour of ClAlPc film
and its formation of a Schottky barrier with Al and In electrodes and
ohmic contact with ITO and Au electrodes. Under low forward bias (Al a
nd In electrodes are negative with respect to ITO) Ohm's law is follow
ed with a thermally activated hole concentration of p(0) = 2.2 X 10(17
) m(-3), a hole mobility mu(p) = 1.2 X 10(-6), m(2) V-1 s(-1) and room
temperature conductivity sigma = 4.8 x 10(-8) (Omega m)(-1). At high
applied voltage there is a space charge limited conductivity (SCLC) co
ntrolled by a discrete trapping level above the valence band edge. The
total trap concentration and depth of trap level are 1.4 X 10(24) m(-
3) and 0.78 eV, respectively, Under reverse bias, the conduction proce
ss is determined by Schottky emission over a potential barrier of heig
ht of 0.65 eV in the low voltage range and the Poole-Frenkel effect fo
r higher voltage. On illumination through the ITO electrode with monoc
hromatic light of 20 mW cm(-2) at 660 nm, the device parameters of the
Al/ClAlPc/ITO and In/ClAlPc/lTO cells were determined. The experiment
al absorption and action spectra data are explained with the help of t
he comprehensive theoretical model proposed by Ghosh and Feng for orga
nic solar cells.