Effect of heat treatment on morphological, structural and optical properties of CoMTPP thin films

Influence of annealing temperature on structural and optical properties of nanocrystalline Platinum octaethylporphyrin (PtOEP) thin films

“…In our study, the improvement in crystal structure of films with the increasing annealing temperature was found from XRD and FESEM results. Similar observation of decrease in the optical band gap with the increase of annealing temperature was reported for several organic semiconductors thin films [2,[9][10][11]. In addition, the decreasing in energy gap may be explained in term of the thermal energy generated by annealing which effected in delocalized p electrons and shift in the relative positions of the valence band (HOMO; p-orbitals) and conduction bands(LUMO; p * -orbitals) [9].…”

“…7 for asdeposited and annealed films. The indirect allowed transition was observed in several metalloporphyrins like NiTPP [2], FeTPPCl [9], CoMTPP [10] and CuTPP [11] thin films. The indirect band gap for PtOEP films is evaluated by extrapolating the linear portion of this plot to (ahm) 1/2 = 0.…”

“…If the absorption is strong, it will cause a change in direction of reflective index and it will return to normal direction after the absorption drops back down to non-absorbing region [46]. This region of strong absorption is referred to as anomalous dispersion [2,[9][10][11]46]. Tsuboi et al, they found the multi-Lorentz oscillator model would be much better than the four-oscillator model to study the optical constants for PtOEP emitting layer in singlelayer in (OLED) device and in thin film grown on quartz plate, but the multi-oscillator model makes the calculation more complicated because of too many parameters [12].…”

“…Tsuboi et al, they found the multi-Lorentz oscillator model would be much better than the four-oscillator model to study the optical constants for PtOEP emitting layer in singlelayer in (OLED) device and in thin film grown on quartz plate, but the multi-oscillator model makes the calculation more complicated because of too many parameters [12]. The behavior of refractive index in this region was observed in several metalloporphyrins like NiTPP [2], FeTPPCl [9], CoMTPP [10] and CuTPP [11] thin films. On the other hand, in the second region k > 600 nm there is no absorption in this region (non-absorbing region see Fig.…”

“…For semiconductor devices like light emitting diodes and solar cells the structural and optical properties are very important, therefore it is essential to investigate how thermal annealing process affects these properties [8]. The effect of thermal annealing process on the optical and structural properties of some metalloporphyrins like FeTPPCl [9], CoMTPP [10] and CuTPP [11] has been studied by El-Nahass et al The clarifications regarding the relation between structural and optical properties have both scientific and technological importance. Few studies have been devoted to the optical properties of PtOEP, focusing mainly on the absorption and emission in liquid solutions and doped films [12][13][14][15][16][17].…”