Bulk heterojunction photovoltaics with improved efficiencies using stem- leaf, shish-kebab and double-fibrillar nano-hybrids based on modified carbon nanotubes and poly(3-hexylthiophene)

摘要

For improving the photovoltaic efficiencies, the conductive ordered and disordered nano-hybrids were developed as morphology mediator based on multi-walled carbon nanotubes (CNTs), their chemically surface modified derivatives, regioregular poly(3-hexyl thiophene) (RR-P3HT) and non-regioregular poly(3-dodecyl thiophene) (PDDT). In unmodified CNTs and their derivatives functionalized with 2-hydroxymethyl thiophene (CNT-f-COOTh, FCNT) and grafted with poly(3-dodecylthiophene) (CNT-g-PDDT, GCNT), double-fibrillar, shish-kebab, and stem-leaf nanostructures were decorated. When the pre-developed FCNT/P3HT and GCNT/P3HT nano-hybrids were applied in thin active layers, a progress was detected in photovoltaic characteristics, in particular for P3HT:GCNT/P3HT devices via larger phase separations. The current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) values ranged in 8.14–8.66 mA/cm2, 49–51%, and 2.55–2.78% for P3HT:GCNT/P3HT systems, respectively. The best photovoltaic features were detected for P3HT:GCNT/P3HT:phenyl-C71-butyric acid methyl ester (PC71BM) devices (Jsc = 9.91–10.22 mA/cm2, FF = 57–59%, and PCE = 3.50–3.74%). The peak values around 69–71% and 52–54% in the external quantum efficiency (EQE) curves were detected at about 550 nm for P3HT:GCNT/P3HT:PCBM and P3HT:GCNT/P3HT devices, respectively.