**Author details**

136 Organic Light Emitting Devices

up to 5%.

**5. Conclusion** 

computational results are compared and discussed.

**Figure 28.** Schematic energy diagram of the proposed bulk heterojunction solar cell.

The photovoltaic efficiency performance data of the photovoltaic cell (power conversion efficiency (PCE) values, including the open circuit voltage (Voc), short circuit current (Jsc), fill factor (FF) and incident-light power (Pin), are derived from the following equation: PCE = Voc. Jsc. FF/Pin. The maximum open circuit voltage (Voc) of the BHJ solar cell is related to the difference between HOMO of the electron donor and LUMO of the electron acceptor, taking into account the energy lost during the photo-charge generation [131-133]. The theoretical values

of open-circuit voltage Voc have been calculated from the following expression [134]:

��� � |������������| − |���������������| − 0.3 Based on this formula, it can be seen that the Voc value of P3HT2BTCz: PCBM is about 0.97 V but it depends on the difference of the output of the electrodes [135]. Starting from the above results, P3HT2BTCz composite seems to be a good candidate for photovoltaic application due to its high Voc and wider absorption range broader than the range of absorption of other copolymers. Based on Scharber model [136], the maximum power-conversion efficiency of the photovoltaic solar cell, with P3HT2BTCz:PC61BM (1:1) composite as active layer can be

The aim of this chapter is to combine experimental analyses and theoretical calculations to present a comprehensive study of the structural and optical properties of organic electronic devices. Based on model compounds, Highest Occupied Molecular Orbital (HOMO), Lowest Unoccupied Molecular Orbital (LUMO) levels, Ionization Potential (IP), Electron Affinity (EA) as well as electronic structures for two samples are examined. The optoelectronic parameters studied here are essential for better understanding of the exchange between polymer and electrodes in PLEDs and PPCs. The experimental and S. Ayachi, A. Mabrouk and K. Alimi\* *Research Unit: New Materials and Organic Electronic Devices (UR 11ES55), Faculty of Sciences of Monastir, University of Monastir, Tunisia* 

M. Bouachrine *UMIM, Polydisciplinary Faculty of Taza, University Sidi Mohamed Ben Abdellah, Taza, Morocco* 
