A novel easily made thienoacene-based organic semiconductor, i.e., dinaphtho[3,4-d:3′,4′-d′]benzo[1,2-b:4,5-b′]dithiophene (Ph5T2), was synthesized in high yield, and its thermal stability, electrochemical properties, thin-film morphology and field-effect mobility were investigated. Ph5T2 exhibit excellent thermal stability with a decomposition temperature (Td) of 427 °C. Thin-film X-ray diffraction (XRD) and atomic force microscopy (AFM) characterizations indicate that Ph5T2 can form highly ordered films with large domain size on the para-sexiphenyl (6P)-modified substrates. Organic thin-film transistors (OTFTs) with top-contact geometry based on Ph5T2 exhibit mobilities up to 1.2 cm2 V−1 s−1 in ambient. The devices are highly stable and exhibit almost no performance degradation during 3 months storage under ambient conditions with relative humidity up to 80%.Graphical abstractHighlights► High mobility: Ph5T2 is the first fused aromatic comprising seven fused rings which shows mobility beyond 1 cm2 V−1 s−1. ► Great device stability even in ambient with humidity up to 80%. ► Ease of mass preparation and unique chemical structure design.

[6,6]-Thienyl-C61-butyric acid ester derivatives with methyl, hexyl and 2-ethylhexyl at the 5-position of thiophene ring (TCBM-Cn, n represents the number of carbon atom in the alkyl chain) were synthesized. Unlike [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), these methanofullerene derivatives ([6,6] adduct) can be directly obtained from the typical diazo addition under mild conditions, and high temperature isomerization is unnecessary. With a hexyl or 2-ethylhexyl group at the 5-position of thiophene, the solubility of TCBM-Cn in chlorobenzene is as high as 180 ± 10 mg ml−1. Bulk heterojunction photovoltaic solar cells were fabricated with a device structure of ITO/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/poly(3-hexylthiophene) (P3HT):TCBM-Cn (1:0.8 w/w)/LiF/Al. The device based-on TCBM-C6 exhibited the best performance with a power conversion efficiency (PCE) of up to 4.26%.

Oligothiophenes (OThs) end-capped with 3-quinolyl or pyridyl with nitrogen atom at meta-, ortho- or para-position were synthesized. The single-crystal structures of the resulting molecules, i.e., o-PyTh4, m-PyTh4, p-PyTh4, QuTh2, and QuTh3, were successfully determined by single-crystal X-ray analysis. Pyridyl end-capped OThs, o-PyTh4, m-PyTh4, and p-PyTh4, adopt the different herringbone packing arrangement in crystals depending on the position of the nitrogen atom because of the presence of weak C−H···N hydrogen bonds. The p-PyTh4 molecules are linked each other along the long axis of the molecules to form the extended chains by C−H···N dimer synthon. For m-PyTh4, the C−H···N interactions two-dimensionally extend through C−H···N trimer synthon. The weak hydrogen-bonding network is much more complex in o-PyTh4 crystals because o-PyTh4 has two crystallographically independent molecules. Two-dimensional (2D) hydrogen-bonding networks arranging along the direction of diagonals in the ab plane are formed by the C−H···N trimer synthon. The crystal packing motifs of 3-quinolyl end-capped OThs are distinctly different from pyridyl end-capped ones. The QuTh2 molecules form a 2D face to face π−π slip stacking driven by the interaction of donor and acceptor segments between the neighboring molecules. For QuTh3, the weak C−H···N hydrogen bonds between the two molecules in the same layer and the CH/π weak interactions together force the molecules to form a sandwich-herringbone crystal packing motif. These results provide a new protocol to control molecular packing arrangement of conjugated oligomers.

[6,6]-Thienyl-C61-butyric acid ester derivatives with methyl, hexyl and 2-ethylhexyl at the 5-position of thiophene ring (TCBM-Cn, n represents the number of carbon atom in the alkyl chain) were synthesized. Unlike [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), these methanofullerene derivatives ([6,6] adduct) can be directly obtained from the typical diazo addition under mild conditions, and high temperature isomerization is unnecessary. With a hexyl or 2-ethylhexyl group at the 5-position of thiophene, the solubility of TCBM-Cn in chlorobenzene is as high as 180 ± 10 mg ml−1. Bulk heterojunction photovoltaic solar cells were fabricated with a device structure of ITO/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/poly(3-hexylthiophene) (P3HT):TCBM-Cn (1:0.8 w/w)/LiF/Al. The device based-on TCBM-C6 exhibited the best performance with a power conversion efficiency (PCE) of up to 4.26%.