Improved hybrid solar cells consisting of vertical aligned cadmium sulfide （CdS） nanorod arrays and interpenetrating polythiophene （P3HT） have been achieved via modification of CdS nanorod surface by using conjugated N719 dye. The complete infiltration of P3HT between CdS nanorods interspacing was verified by scanning electron microscopy. By employing absorption and photoluminescence spectra, and current-voltage characterization the interaction between N719 molecules and CdS nanorods/P3HT interface was explored, and the role of N719 dye on the improvement of device performance was discussed.
A n-type small molecule DC-IDT2E with 4,4,9,9-tetrakis（4-hexylphenyl）-indaceno[1,2-b：5,6-bt]dithiophene as a central building block, furan as rr-bridges, and 1,1 -dicyanomethylene-3-indanone as end acceptor groups, was synthesized and used as an electron acceptor in solution-processed organic solar cells （OSCs）. DC-IDT2F exhibited good thermal stability, broad and strong absorption in 500-850 rim, a narrow bandgap of 1.54 eV, LUMO of-3.88 eV, HOMO of-5.44 eV and an electron mobility of 6.5 × 10-4 cm2/（V.s）. DC-IDT2F-based OSCs with conventional and inverted structures exhibited power conversion efficiencies of 2.26 and 3.08% respec- tively. The effect of vertical phase separation and morphology of the active layer on the device performance in the two structures was studied.
Organic small molecules(TPA-BT3T,TPA-PT3T,and TPA-DFBT3T)using triphenylamine as a donor unit,terthiophene as a bridge,and benzo-2,1,3-thiadiazole(BT),[1,2,5]thiadiazolo[3,4-c]pyridine(PT)or 5,6-difluorobenzo[c][1,2,5]thiadiazole(DFBT)as an acceptor unit were designed and synthesized through Suzuki coupling reactions.These molecules exhibited good thermal stability with decomposition temperatures over 380°C and broad absorption from 300 to 700 nm.Photovoltaic devices were fabricated with these small molecules as donors and PC71BM as an acceptor.The TPA-BT3T based devices exhibited a power conversion efficiency of 2.89%,higher than those of the TPA-PT3T-and TPA-DFBT3T-based devices(1.34%and1.54%respectively).The effects of electron-withdrawing units on absorption,energy level,charge transport,morphology,and photovoltaic properties also were investigated.
Light trapping based on the localized surface-plasmon resonance(LSPR)effect of metallic nanostructures is a promising strategy to improve the device performance of organic solar cells(OSCs).We review recent advances in plasmonic-enhanced OPVs with solution-processed metallic nanoparticles(NPs).The different types of metallic NPs(sizes,shapes,and hybrids),incorporation positions,and NPs with tunable resonance wavelengths toward broadband enhancement are systematically summarized to give a guideline for the realization of highly efficient plasmonic photovoltaics.
