Thiadiazoloquinoxaline-Fused Acenaphthenequinone imide: A Highly Electron-Withdrawing Acceptor for Ambipolar Semiconducting Polymers with Strong Near-Infrared Absorption

Abstract

A hitherto unreported heterocyclic imide, thiadiazolo[3,4-g]quinoxaline-fused acenaphthenequinone imide acceptor (TQAI), is designed and synthesized by incorporating an auxiliary electron-deficient thiadiazolo[3,4-g]quinoxaline (TQ) annulated in the lateral direction of the acenaphthenequinone imide skeleton. This molecular design makes it possible to generate strong electron affinity by integrating the highly electron-deficient TQ unit with the dicarboxylic acid imide groups. In addition, a largely π-extended and S/N-enriched π-conjugated structure can be produced, which facilitates both intermolecular and intramolecular interactions. As a result, the alternating arrangement of TQAI acceptor and thiophenederivative donor segments, such as 2,5-bis(3-(2-decyltetradecyl)thiophen-2-yl)thieno-[3,2-b]thiophene or 3,3‴-bis(2-decyltetradecyl)-2,2′:5′,2″:5″, 2‴-quaterthiophene, in the polymer main chain, endows the target D−A conjugated polymers with desirable photophysical and electrochemical properties. These properties include deep lowest unoccupied molecular orbital levels (LUMO < −3.80 eV), narrow optical band gaps (as low as 0.84 eV), strong light-capturing ability in the second near-infrared window, and strong solid-state organization with a preferred face-on orientation. The organic field-effect transistors, which were made with our synthesized polymers, exhibit typical ambipolar charge transport in an inert atmosphere. PTQAIT-2T shows maximum hole and electron mobilities of 8.1 × 10 −3 and 3.6 × 10 −2 cm 2 V −1 s −1 , respectively. In particular, with a C 60 layer, which is added to facilitate efficient electron trapping and exciton dissociation, the bilayer C 60 /PTQAIT-2T phototransistors show a pronounced photosensitivity of 1780, which is 50 times higher than that of pristine PTQAIT-2T devices.

Ladder‐Like Difluoroindacenodithiophene‐4,9‐dione Derivative: A New Acceptor System for High‐Mobility n‐Type Polymer Semiconductors

“…Such remarkable red‐shift in absorption band of the polymers compared with the FIDTO‐R acceptor unit is due to the strong D−A interaction between the electron‐deficient FIDTO‐R units and the electron‐donating thiophene or selenophene units. [ 52,53 ] Despite some variations in the polymer chain structure, two polymers show an identical dual‐band absorption, which is similar to their parent unit (FIDTO‐R) and most reported D‐A copolymers. [ 52,53 ] Note that the absorption peaks and solution color of the polymers are highly related to the donor strength.…”

“…[ 52,53 ] Despite some variations in the polymer chain structure, two polymers show an identical dual‐band absorption, which is similar to their parent unit (FIDTO‐R) and most reported D‐A copolymers. [ 52,53 ] Note that the absorption peaks and solution color of the polymers are highly related to the donor strength. For example, the selenophene‐linked PFIDTO‐Se exhibits a strong π−π* transition peak at 491 nm and a weak ICT peak at 782 nm, both of them show obvious red‐shifts when compared to the thiophene‐linked PFIDTO‐T.…”

Toward Efficient Charge Transport of Polymer-Based Organic Field-Effect Transistors: Molecular Design, Processing, and Functional Utilization

“…The low bandgap semiconducting polymers showed high near-infrared sensitivity but usually possessed much inferior carrier mobilities. 52,53 Therefore, both high nearinfrared sensitive semiconducting small molecules and highperformance polymers have been combined for use in these OFET-based integrated applications. 54−56 Light-sensitive elements, such as rods and cones, play significant roles in the process of human visual perception that transduces both the intensity and color information on the incident light to neural signals.…”

“…To date, semiconducting polymers with both high near-infrared sensitivity and high electrical performance remain a challenge. The low bandgap semiconducting polymers showed high near-infrared sensitivity but usually possessed much inferior carrier mobilities. , Therefore, both high near-infrared sensitive semiconducting small molecules and high-performance polymers have been combined for use in these OFET-based integrated applications. − …”

Copolymers Containing 1-Methyl-2-phenyl-imidazole Moieties as Permanent Dipole Generating Units: Synthesis, Spectroscopic, Electrochemical, and Photovoltaic Properties

“…In the majority of cases, they are low band gap semiconductors exhibiting appropriate ionization potential (IP) and electron affinity (EA) values to assure their ambipolarity. As a result, they can serve as components of active layers in various types of ambipolar organic field-effect transistors, characterized by well-balanced n-type and p-type electrical transport [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ]. Low ionization potential (IP) and high electron affinity (EA) of D–A and D–A–D polymers, together with the presence of several chromophore groups, promote their reversible electrochemical and spectroelectrochemical behavior [ 16 ].…”