Unveiling the Interplay among End Group, Molecular Packing, Doping Level, and Charge Transport in N‐Doped Small‐Molecule Organic Semiconductors

Abstract

Doped small molecules with high electrical conductivity are desired because they typically show a larger Seebeck coefficient and lower thermal conductivity than their polymer counterparts. However, compared with conjugated polymers, only a few small molecules can show high electrical conductivities. In this study, three n-type small-molecule organic semiconductors with different end functional groups are synthesized to explore the reasons for the low electrical conductivity issue in n-doped small-molecule semiconductors. Charge carrier mobility and doping level are usually considered as two major parameters for achieving high electrical conductivity. TDPP-ThIC with high electron mobility of 0.77 cm 2 V −1 s −1 and high electron affinity, which can be easily n-doped; however, it only displays an electrical conductivity ≈10 −3 S cm −1 . To explore the reasons, the single crystal structure of TDPP-ThIC and the grazing incidence wide-angle X-ray scattering of its n-doped films are carefully analyzed. TDPP-ThIC with a 1D column packing is disclosed and easily distorted by the enthetic n-dopants, which damages the charge transport pathways, and thereby results in low electrical conductivity. The results suggests that only high intrinsic charge carrier mobility and high doping level cannot guarantee high electrical conductivity, and keeping good charge transport pathways after doping is also critical.

Novel A-π-D-π-A type non-fullerene acceptors of dithienyl diketopyrropopyrrole derivatives to enhance organic photovoltaic applications: a DFT study

“…The MPW1PW91/6-13G(d,p) method provided an absorption maximum at 739 nm that was in close correlation with the experimental value (710 nm in chlorobenzene) as mentioned in the literature. 33 Therefore, this approach was chosen as the optimum method for further research of all the formulated compounds. In Fig.…”

“…Spectral depiction of λ max was achieved through Origin 6.0 software. 30 UV-visible absorption 31,32 of TMR was contrasted with the cited (710 nm in chlorobenzene) 33 value to determine the best functional. Closeness to the experimentally determined maximum absorption of TMR was achieved by MPW1PW91/6-31G(d,p).…”

Quantum modeling of dimethoxyl-indaceno dithiophene based acceptors for the development of semiconducting acceptors with outstanding photovoltaic potential

“…[8][9][10][11][12][13] In particular, n-type organic semiconductor (n-OS) based small acceptor molecules [14][15][16][17] with a low bandgap (E gap ), when combined with a p-type donor polymer having a medium E gap , have shown remarkable optoelectronic performance. [18][19][20] The PCE of polymer based solar cells having an n-OS as an accepting moiety has increased to a 14%, surpassing the limit for PSCs to be used in practical settings. [21][22][23] The majority of highly efficient donor and acceptor optoelectronic materials, though, currently contain complex chemical geometries.…”

Enriching NLO efficacy via designing non-fullerene molecules with the modification of acceptor moieties into ICIF2F: an emerging theoretical approach

“…29,30 Moreover, the extended p-conjugation with intense absorption parameters of fullerene-free chromophores have been enhanced via attachment of electron-decient terminal groups (cyano, nitro and halogens groups) over the skeleton of the nonfullerene acceptors (NFAs). 31,32 Furthermore, the nature and conjugated length of donor and acceptor parts are also important to design interesting NLO materials. 33 The synthesized compound (ICIF2F) is reported in the literature 34 and according to our best insights, its NLO study has not yet been published.…”