This paper discussed the effect of different thermal evaporation treatments for nanocomposited MEH-PPV:CNTs thin films towards the performance of organic solar cells. The configuration of the organic solar cells is ITO/MEH-PPV:CNTs/Au. The heating temperature was varied from, as deposited,50°C,75°C, and100°C. From the results, we observed that the efficiency increase slightly before decreasing back at100°C. The highest efficiency was solar cells heated at75°C with efficiency 0.001% which is supported by theI-Vcharacteristics and also by the absorption spectra.

This work focus on optical band gap of nanocomposited MEH-PPV:CNTs thin film. In this research we investigate the behavior of optical band gap when the composition of CNTs powder is increased which directly influence the thickness of the thin film. The experimental process entailed for the black powder of CNTs to be first annealed at 450 °C before mixing it with the polymer solution to ensure that the impurities in the CNTs are all removed. The 20 mg MEH-PPV polymer was dissolved in an aromatic solvent which is toluene with a concentration of 1:1. The composite materials were prepared by adding appropriate amounts of CNTs powder (1, 2, 3 and 4 wt%) into the polymer solution to make various ratios of CNTs powder/polymer composites. The optical properties of the thin film were analyzed by using Perkin Elmer Lambda 750 UV/Vis Spectrometer. Thickness of the thin film is measured using Surface profiler Veeco Dektak 150. In this paper, the optical band gap energy is derived by assuming a direct transition of electron between the edge of the valence band and the conduction band. Our results demonstrates that as the thickness decrease from 62, 60, 59, 58 and 57 nm, the optical band gap showed slight decrement from 2.07, 2.07, 2.05, 2.01 and 2.00 eV for respectively.

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Bulk heterojunction solar cell has received significant attention over the past decade due to low cost power generation and the potential to develop a clean renewable energy source [. We investigated the effect of different type of metal cathodes on the power conversion efficiency of bulk heterojunction solar cell based on a blend of conjugated polymer poly [2-methoxy 5-(2-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) with titanium dioxide (TiO2). In this case of study, Aluminum (Al) and gold (Au) has been chosen as the metal cathode due to the difference of work function and their wide application in hybrid solar cell. We show that the choice of metal cathode plays a role in determining overall device efficiency through their impact on short-circuit current, open circuit voltage and fill factor due to the influence of work function. It is found that the device employing Al metal cathode which has low work function is showing a comparable performance to the Au metal electrode with fill factor of over 20 % and a power conversion efficiency of 3.3x10-3 %. Overall it is demonstrated that the matching between the work function of the cathode and photoactive layer MEH-PPV: TiO2 is the most important factor towards best bulk heterojunction solar cell performance.