Effect of Iodine Concentration in MWCNTs for MEH-PPV Based Organic Solar Cell Applications

In general, Iodine doping concentration can affect the conductivity of the CNTs and explicitly the efficiency of organic solar cells. Iodine is a p-type dopant and when doped into MWCNTs it form an electron acceptor in the form of (I3)- or (I5)-. Therefore, electron transfer from Iodine to MWCNTs can generate free hole carriers. This free hole carriers is then collected by the electrodes. However, the generated free carriers depend on the concentration Iodine being used. It can be seen that as the concentration of Iodine increase from undope, 40 mg, 60 mg and 1 g, the I-MWCNTs are well dispersed in the polymer matrix. The results obtained reveal that the films are smooth as the concentration of Iodine increased. This shows that the agglomerations of the CNTs are less when there is more Iodine being doped with the CNTs. It can also be observed that as the Iodine concentration increased the film thickness decreased. In this work, the possibility to get efficiency with thickness of less than 60 nm is proved and the obtained efficiency with thickness about 51 nm at 1 g Iodine doping has been recorded with 8.01 x 10-4 %.