**Acknowledgements**

Finally, in order to evaluate the electrical properties of the thin films, the four-point technique was employed, using the glass substrate with an ITO conducting contact. This study was performed on the sample labelled *Thin Film 7*, which was the one having the lowest optical

versus photon energy *hν* of *Thin Film 7*.

**Figure 7.** *I*-*V* characteristics of *Thin Film 7:* (a) ITO is positively biased and (b) ITO is negatively biased.

*Film 7* under different illumination types (yellow light, white, blue, orange, green, infrared, UV and dark [no light]). Regardless of the wavelength of the incident radiation, the thin film follows the same behaviour. At lower voltages (around 10 V), ohmic conduction is evident, while space-charge limited conductivity (SCLC) governed by an exponential trap distribution is found at higher voltages. On the other hand, the *I-V* characteristics display symmetric

. **Figure 7** shows the *I-V* characteristics of *Thin* 

gap. The film had a surface area of 2.16 cm2

**Figure 6.** Plot of **(α***h***ν)1/2** and **(α***h***ν)<sup>2</sup>**

38 Phthalocyanines and Some Current Applications

The authors wish to thank the technical support of M.I. Mariel Leyva-Esqueda (Universidad Anáhuac) for technical help. María Elena Sánchez-Vergara gratefully acknowledges the financial support of Universidad Anáhuac México under grant INNADBSEVM140129141.
