Phthalimide–thiophene-based conjugated organic small molecules with high electron mobility

Abstract

High electron mobility in a series of phthalimide–thiophene small molecules has been demonstrated when incorporated into thin film transistors.

The influence of molecular geometry on photophysical properties and self-assembly of phthalimide end-capped thiophene-based organic molecules

“…The absorption maximum is blue shifted to 385 nm after transitioning from solution into thin-film, due to the tendency of PthTh 2 Pth to self-assemble in an ordered face to face orientation (Haggregates). 19,20 The absorption maxima of (PthTh) 3 In comparison to PthTh 2 Pth, the absorption maximum of (PthTh) 3 BZ in solution is shifted hypsochromically (380 versus 420 nm). This is attributed to the meta-substituents at the benzene ring which result in reducing the π-conjugation length.…”

“…Similar to PthTh 2 Pth, 19,20 The photophysical properties of compounds 1, 2 and 3 were measured by UV-vis and fluorescence spectroscopy. Fig.1 shows the normalized absorption and emission spectra of the three compounds in chloroform solution and their optical absorption in thin films.…”

“…18 Recently, our group has reported the optimized synthesis and opto-electronic characteristics of phthalimide end-capped oligothiophene small molecules that bear terminal alkyl chains. 19,20 When combined with poly(3-hexylthiophene) (P3HT) in BHJ solar cell, bithiophene core molecule (PthTh 2 Pth (1), Fig.1.A) exhibited a high open circuit voltage (V OC ~0.94 V) and low PCE (~0.2%). The low efficiency was attributed to the tendency of PthTh 2 Pth to undergo crystallization from donor-acceptor blends, which result in formation of micron-size domains compared to exciton diffusion length.…”

High open circuit voltage organic solar cells based upon fullerene free bulk heterojunction active layers

“…To assess the PL quenching of P3HT by PhtTh 2 Pth, the PL intensity of blend films of various donor-acceptor ratios spun from 20 mg mL −1 solutions were measured and compared with the intensity of neat P3HT films spun from solutions containing the same amount of polymer. It is worth mentioning that considering PhtTh 2 Pth is emissive in the range of 500-600 nm, 40 we measured the PL spectral intensity of both neat P3HT and blend films excited at the absorption maxima of PthTh 2 Pth, and noted that the emission spectra were similar. The PL spectra of both neat and blend films of various donor-acceptor ratios are presented in Fig.…”

“…These peaks were displayed at angles of 8.2°and 13.7°and are in good agreement with the spectrum of drop-cast PthTh 2 Pth films. 40 Peak broadening may indicate either the formation of small crystal domains (<1 m) or the presence of a large density of lattice defects. 71 The annealed neat P3HT (Fig.…”