Introducing a Nonvolatile N‐Type Dopant Drastically Improves Electron Transport in Polymer and Small‐Molecule Organic Transistors

Abstract

Molecular doping is a powerful yet challenging technique for enhancing charge transport in organic semiconductors (OSCs). While there is a wealth of research on p-type dopants, work on their n-type counterparts is comparatively limited. Here, reported is the previously unexplored n-dopant (12a,18a)-5,6,12,12a,13,18,18a,19-octahydro-5,6-dimethyl-13,18[1′,2′]-ben- zenobisbenzimidazo [1,2-b:2′,1′-d]benzo[i][2.5]benzodiazo-cine potassium triflate adduct (DMBI-BDZC) and its application in organic thin-film transistors (OTFTs). Two different high electron mobility OSCs, namely, the polymer poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6diyl]-alt-5,5′-(2′-bithiophene)] and a small-molecule naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malononitrile groups (NDI-DTYM2) are used to study the effectiveness of DMBI-BDZC as a n-dopant. N-doping of both semiconductors results inOTFTs with improved electron mobility (up to 1.1 cm 2 V −1 s −1 ), reduced threshold voltage and lower contact resistance. The impact of DMBI-BDZC incorporation is particularly evident in the temperature dependence of the electron transport, where a significant reduction in the activation energy due to trap deactivation is observed. Electron paramagnetic resonance measurements support the n-doping activity of DMBI-BDZC in both semiconductors. This finding is corroborated by density functional theory calculations, which highlights ground-state electron transfer as the main doping mechanism. The work highlights DMBI-BDZC as a promising n-type molecular dopant for OSCs and its application in OTFTs, solar cells, photodetectors, and thermoelectrics.

N-Doping improves charge transport and morphology in the organic non-fullerene acceptor O-IDTBR

“…18,6 Despite these difficulties, we recently identified [1,2- (Figure 1d) as a suitable charge transfer n-dopant. 13 Other n-dopants -that utilise alternative doping mechanisms -have also been identified in the literature, with two exemplary materials being tetra-n-butylammonium fluoride (TBAF) (Figure 1b), 12,19,20 and 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,Ndimethylbenzenamine (N-DMBI) (Figure 1c). 21,22,14 To test the applicability of DMBI-BDZC, TBAF and N-DMBI as n-dopants in O-IDTBR, we studied each system using EPR.…”

“…2 This is further supported by the fact that Lewis acids, such as B(C 6 F 5 ) 3 and Zn(C 6 F 5 ) 2 , have recently been shown to play the role of both molecular dopant and morphology modifiers. 10,11 Along with the steady growth in the library of n-type molecular dopants, 12,13,14 these latest observations are important for solution-processed n-type small-moleculesespecially for those that have already shown to be exceptional OSCs for various applications. For example, materials such as nonfullerene acceptors (NFAs) have received great interest in recent years in the field of organic photovoltaics (OPVs).…”

An Organic Borate Salt with Superior p‐Doping Capability for Organic Semiconductors

“…[1][2][3][4] Molecular dopants were employed to enhance the performance of organic light emitting diodes (OLEDs), [5,6] organic photovoltaic cells (OPVCs), [7,8] and organic field effect transistors (OFETs). [9][10][11] These doping strategies were recently instrumental for achieving high hole [12] and electron [13] mobility in transistors, enabling coherent charge transport in polymers, [14] boosting the power conversion efficiency in organic solar cells, [15] and demonstrating high-performance thermoelectric organic materials. [16] The nature of charge carriers formed upon doping conjugated polymers with a nondegenerate ground state, like the most widely studied poly(3-hexylthiophene) (P3HT), has been a widely discussed topic.…”

Organic Complementary Inverters Based on Vertical-Channel Dual-Base Thin-Film Transistors with Time Constants < 10ns

“…Although channel doping has been successfully demonstrated in organic transistors [7][8][9] , it may not be the best strategy for threshold voltage tuning in OTFTs due to deterioration of charge carrier mobility, reduction of on/off-ratio, or insu cient controllability. An alternative method for threshold voltage tuning is the use of dual-gate transistors.…”