Saturation/unsaturation of P3HT:PC71BM photovoltaics with CNT derivatives and correlated supramolecules

Three different types of multi-walled carbon nanotube (CNT) derivatives such as unmodified CNT, grafted-CNT (CNT-graft-poly(3-hexylthiophene) (P3HT)), and pre-designed supramolecular nanostructure (CNT-graft-poly(3-dodecylthiophene) (PDDT)/P3HT) with weight percentages of 0.0005-50 wt% were applied to be incorporated as third components in P3HT:phenyl-C71-butyric acid methyl ester (PC71BM) photovoltaics for studying the saturation thresholds. The procedure introduced in this work paved the way for neutralizing the disadvantages of CNT precursors and simultaneously using their advantages in P3HT:PC71BM photovoltaics. The grafted-CNTs increased the capacity of active layers for acceptance of CNT and thus increased the cell performance (0.5 wt%, 4.09%). Interestingly, the pre-crystallized CNT/P3HT supramolecules eliminated the saturation point in P3HT:PC71BM solar cells, thereby the photovoltaic parameters were continuously raised even up to 50 wt%. The highest hole (mu(h)) and electron (mu(e)) mobilities belonging to P3HT:PC71BM:supramolecule devices (7.4 x 10(-4) and 8.6 x 10(-3) cm(2 )/V.s) led to the highest photovoltaic characteristics (13.20 mA/cm(2) , 66% and 5.31%).