Optoelectronic and nonlinear optical properties of tBu₄PcTiO/polymer composite materials

The optoelectronic and nonlinear optical (NLO) properties of a soluble 2,(3)-(tetra-tert-butylphthalocyaninato)titanium(IV) oxide (tBu₄PcTiO) in solutions and in the solid states have been described. The nonlinear response demonstrated that tBu₄PcTiO exhibited strong RSA at 532 nm for both solution and solid-state based experiments. The decrease in the effective intensity dependent nonlinear absorption coefficient with increasing input intensities possibly results from high order triple state transitions of the excited-state population. No evidence of film fatigue or degradation was observed in the PMMA/tBu₄PcTiO film, after numerous scans at varying laser intensity. The doping of tBu₄PcTiO into poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylene-vinylene] (MEH-PPV) results in the apparent increases of the open circuit voltage (Voc) and the short circuit photocurrent density under illumination with 40 mW cm^-2 white-light. The light absorption of tBu₄PcTiO incorporated into polymer represents the dominant contribution to the enhancement of the photocurrent. The dependence of the short circuit photocurrent in an ITO/tBu₄PcTiO-doped MEH-PPV/Al cell on the incident light intensity (I_in) between 30 and 200 mW cm^-2 was also investigated.