An attempt was made to widen the photosensitivity
spectral range of poly(3-hexylthiophene)-fullerene blend by adding an extra
electron donor — a newly synthesized soluble phthalocyanine derivative
(SnClPc) having the electron absorption band at 708 nm. As the electron
acceptor, home-synthesised di(ethoxycarbonyl) methano-fullerene carboxylate
(C61(CO2Et)2) was used, and as the hole transporter — the
regioregular poly 3-hexylthiophene (P3HT). The sandwich-type samples were
prepared on an ITO glass substrate by coating it with a 30–50 nm thick
PEDOT:PSS layer followed by a ~100 nm thick P3HT:C61(CO2Et)2:SnClPc
blend. For the top electrodes In or Au
were used. Spectral dependences of the PV effect and of the influence of
external magnetic field (0–3000 Oe) on it were studied in the 370–1000 nm
spectral range in vacuum of ~10-6 Torr. Significant
photosensitivity of the blend was observed in the 370–800 nm spectral range.
However, the short-circuit photocurrent quantum efficiency evaluated for
absorbed light was found to be 4 times higher for illumination in the P3HT
absorption band as compared with that in the SnClPc band. The observed
magnetic field effect shows that the low IPCE values may be explained by the
space charge formation in the samples, leading to a strong geminate
recombination of CP states.