In this work, OPVs with an active layer composed by P3HT (poly(3-hexylthiophene)) and PCBM ([6,6]-phenyl-C61- butyric acid methyl ester) was fabricated by spin coating technique and studied after post-thermal annealing. The devices were annealed at temperatures ranging from 150 °C to 175 °C, showing an increase in efficiency at 160 °C, decreasing after. In order to achieve a physical model for this behavior, dc and ac measurements, together morphology analysis was made and correlated. Under dc conditions, the overall figures of merit were measured and fitted to the physical models using genetic algorithms; by ac measurements, the capacitance and loss dependence on frequency were studied and equivalent circuit models were obtained. Capacitance – voltage behavior was also analyzed. The morphology of OPV active area film was investigated by Atomic Force Microscopy (AFM) in both tapping and current sensing methods. The OPVs exhibit efficiencies ranging from 1.2 to 3%, with fill-factors (FF) ranging from near 50% to near 70%. The relaxation frequencies can be correlated with the efficiency behavior, and with the micro electrical map obtained (and correlated with morphology) by AFM-current sensing. It was shown that how post-thermal annealing changes the micro electrical patterning and therefore, a suitable relationship with macroscopic behavior can be established.
OLEDs for lighting became of high relevance, although challenges in the uniformity and thermal effects. In this work, White-OLEDs with 16 cm<sup>2</sup> emitting area was made with wide color temperature range (3200 K to 10500K) and color rendering index near 90. The CIE coordinates are stable with applied voltage. Thermal images shows 60°C in the center decreasing to 35°C at the border. This effect was study by a scalar electro-thermal model, considering the substrate, electrodes and organic layers. The thermal changing ratio in the series resistance and forward voltage obtained was of - 70 mΩ/°C and -10 mV/°C respectively.