Packing Effect on the Transfer Integrals and Mobility in α,α′-bis(dithieno[3,2-b:2′,3′-d]thiophene) (BDT) and its Heteroatom-Substituted Analogues

Theoretically calculated mobility has revealed that BDT is a hole transfer material, which is in good agreement with experimental investigations. The BDT, NHBDT, and OBDT are predicted to be hole transfer materials in the C2/c space group. Comparatively, hole mobility of BHBDT is 7 times while electron mobility is 20 times higher than the BDT. The packing effect for BDT and designed crystals was investigated by various space groups. Generally, mobility increases in BDT and its analogues by changing the packing from space group C2/c to space groups P1 or P (1) over bar. In the designed ambipolar material, BHBDT hole mobility has been predicted 0.774 and 3.460 cm(2) Vs(-1) in space groups P1 and P (1) over bar, which is 10 times and 48 times higher than BDT (0.075 and 0.072 cm(2) Vs(-1) in space groups P1 and P (1) over bar), respectively. Moreover, the BDT behaves as an electron transfer material by changing the packing from the C2/c space group to P1 and P (1) over bar.