Search

Emissive organic semiconductors are highly demanding for organic light‐emitting transistors (OLETs) and electrically pumped organic lasers (EPOLs). However, it remains a great challenge to obtain organic semiconductors with high carrier mobility and high photoluminescence quantum yield simultaneously. Here, a new design strategy is reported for highly emissive ambipolar and even n‐type semiconductors by introducing perfluorophenyl groups into polycyclic aromatic hydrocarbons such as perylene and anthracene. The results reveal that 3,9‐diperfluorophenyl perylene (5FDPP) exhibits the ambipolar semiconducting property with hole and electron mobilities up to 0.12 and 1.89 cm2 V−1 s−1, and a photoluminescence quantum yield of 55%. One of the crystal forms of 5FDPA exhibits blue emission with an emission quantum yield of 52% and simultaneously shows the n‐type semiconducting property with an electron mobility up to 2.65 cm2 V−1 s−1, which is the highest value among the reported organic emissive n‐type semiconductors. Furthermore, crystals of 5FDPP are utilized to fabricate OLETs by using Ag as source–drain electrodes. The electroluminescence is detected in the transporting channels with an external quantum efficiency (EQE) of up to 2.2%, and the current density is up to 145 kA cm−2, which are among the highest values for single‐component OLETs with symmetric electrodes. [ABSTRACT FROM AUTHOR]

A perylene five-membered ring diimide, PDI39, was developed as a new electron-deficient building block for n-type semiconductors. The π-expanded conjugated molecules containing azulenes were synthesized from PDI39. These conjugated molecules show helical geometry and near-infrared absorption up to 810 nm. [ABSTRACT FROM AUTHOR]

Diketopyrrolopyrrole (DPP) as a building block has been intensively investigated for organic semiconductors and light emitting materials. The synthesis of N‐aryl DPPs remains challenging. Herein, we firstly report a new easily handled synthetic method toward N‐aryl DPPs through H‐DPP with diaryliodonium salt in the presence of CuI, which shows broad reaction scope. Sixteen N‐aryl DPPs, including phenyl, furan and thiophene as flanking aromatic groups, were synthesized with yields up to 78 %. These N‐aryl DPPs are fluorescent in both solutions and solid states, with quantum yields up to 96 % and 40 %, respectively. Moreover, we show that the reaction between H‐DPP and diaryliodonium salt can lead to π‐expanded DPPs by using Pd(OAc)2 as catalyst. Nine π‐expanded DPPs were obtained in 27–61 % yields. These π‐expanded DPPs exhibit good semiconducting properties with hole mobility of 0.71 cm2 V−1 s−1, demonstrating that they are useful building blocks for high performance organic semiconductors. [ABSTRACT FROM AUTHOR]

Conjugated molecules with low lying LUMO levels are demanding for the development of air stable n‐type organic semiconductors. In this paper, we report a new A‐D‐A′‐D‐A conjugated molecule (DAPDCV) entailing diazapentalene (DAP) and dicyanovinylene groups as electron accepting units. Both theoretical and electrochemical studies manifest that the incorporation of DAP unit in the conjugated molecule can effectively lower the LUMO energy level. Accordingly, thin film of DAPDCV shows n‐type semiconducting behavior with electron mobility up to 0.16 cm2⋅V−1⋅s−1 after thermal annealing under N2 atmosphere. Moreover, thin film of DAPDCV also shows stable n‐type transporting property in air with mobility reaching 0.078 cm2⋅V−1⋅s−1. [ABSTRACT FROM AUTHOR]

New arylacetylene-substituted naphthalene diimides (NDIs) 1-6, with both light-emitting and semiconducting functions, are reported. Among them, the crystal structure of 1 was determined. On the basis of their reduction potentials and thin-film absorption spectra, the HOMO/LUMO energies of these modified NDIs were estimated. The results reveal that their HOMO/LUMO energies are slightly affected by the flanking aryl groups. The emission colors of these NDIs vary from green to red, and interestingly, they show aggregation-induced emission enhancement behavior with fluorescence quantum yields reaching 9.86 % in the solid state. Microrods of 1, 3, and 5 show typical optical wave-guiding behavior with relatively low optical-loss coefficients. Organic field-effect transistors with thin films of these NDIs were fabricated with conventional techniques. The results indicate that thin films of 2, 4, and 6, with long and branched alkyl chains, show air-stable n-type semiconducting properties with electron mobilities of up to 0.035 cm2 V−1 s−1 after thermal annealing, whereas 1, 3, and 5, with short alkyl chains, behave as n-type semiconductors under a nitrogen atmosphere with electron mobilities of up to 0.075 cm2 V−1 s−1 after thermal annealing. [ABSTRACT FROM AUTHOR]

In this paper, we report the design, synthesis and semiconducting behavior of two conjugated D-A polymers BPDDTE and BPDBDTE which entail BPD, a Pechmann dye framework, as electron accepting moieties and ( E)-1,2-di(thiophen-2-yl)ethane with and without alkyl chains as electron donating moieties. They both show very narrow bandgaps below 1.3 eV. Based on the characterization of the field-effect transistors, thin film of BPDDT exhibits ambipolar semiconducting properties with hole and electron mobilities reaching 0.245 and 0.095 cm2·V????????????1·s−1, respectively, after thermal annealing. Similarly, BPDBDTE with more alkylchains shows ambipolar semiconducting behavior with hole mobility and electron mobilities reaching 0.109 and 0.081 cm2·V−1·s−1. Furthermore, BPDBDTE shows good solubilities in several common organic solvents and thus is easily solution-processible. Thus, BPDBDTE is potentially processible with inkjet printing and roll-to-roll printing techniques. [ABSTRACT FROM AUTHOR]

Two diketopyrrolopyrrole (DPP)-based donor-acceptor (D-A) conjugated molecules, DPP-F and DPP-2F, which contain E-(1,2-difluorovinyl) moieties, are reported. The LUMO energies of DPP-F and DPP-2F were estimated to be −3.49 and −3.70 eV, respectively, based on their redox potentials and absorption spectral data; these values were clearly lowered because of the incorporation of electron-withdrawing E-(1,2-difluorovinyl) moieties. Organic field-effect transistors (OFETs) with thin films of DPP-F and DPP-2F were successfully fabricated with conventional techniques. Based on the respective transfer and output characteristics measured in an inert atmosphere, thin films of DPP-2F display ambipolar semiconducting behavior with hole and electron mobilities reaching 0.42 and 0.80 cm2 V−1 s−1, respectively. The as-prepared OFET of DPP-2F already shows high hole and electron mobilities that are not influenced remarkably by thermal annealing. For thin films of DPP-F, only p-type semiconducting behavior was observed in both an inert atmosphere and air, and the hole mobility increased to 0.1 cm2 V−1 s−1 after thermal annealing. XRD and AFM studies were performed with thin films of DPP-F and DPP-2F after annealing at different temperatures. [ABSTRACT FROM AUTHOR]

The article "Theo Murphy International Scientific Meeting Between the UK and China on the Chemistry and Physics of Functional Materials" by Wenping Hu et al. is cited.

Inthis paper, we report the design, synthesis and semiconductingbehavior of two conjugated D–A polymers P-BPDTTand P-BPDBTwhich entail BPD, a Pechmanndye framework, as electron accepting moieties, and thieno[3,2-b]thiophene and 2,2′-bithiophene as electron donatingmoieties. Their HOMO/LUMO energies and bandgaps were estimated basedon the respective cyclic voltammgrams and absorption spectra of thinfilms. P-BPDTTpossesses lower LUMO level and narrowerbandgap than P-BPDBT. On the basis of the characterizationof the field-effect transistors, a thin film of P-BPDTTexhibits ambipolar semiconducting properties with hole and electronmobilities reaching 1.24 cm2V–1s–1and 0.82 cm2V–1s–1, respectively, after thermal annealing. In comparison,thin film of P-BPDBTonly shows p-typesemiconducting behavior with hole mobility up to 1.37 cm2V–1s–1. AFM and XRD studieswere presented to understand the interchain arrangements on the substratesand the variation of carrier mobilities. [ABSTRACT FROM AUTHOR]

In this paper, we report the synthesis and characterizationoftwo new D-A-D molecules (E)-5,5′-bis(5-(benzo[b]thiophen-2-yl)thiophen-2-yl)-1,1′-bis(2-ethyl-hexyl)-[3,3′-bipyrrolylidene]-2,2′(1H,1′H)-dione (BTBPD) and (E)-5,5′-bis- (5-(benzo[b]furan-2-yl)thiophen-2-yl)-1,1′-bis(2-ethylhexyl)-[3,3′-bipyrrolylidene]-2,2′(1H,1′H)-dione (BFBPD). They entail bipyrrolylidene-2,2′(1H,1′H)-dione (BPD, known as Pechmann dye) as theelectron-accepting core that is flanked by two benzo[b]thiophene moieties and two benzo[b]furan moieties,respectively. Crystal structures of BTBPDand BFBPDprovide solid evidence for the intermolecular donor–acceptor(D-A) interactions, which are favorable for improving charge transportperformance. Organic field-effect transistors (OFETs) were preparedbased on thin films of BTBPDand BFBPDthroughsolution-processed technique. OFETs of BTBPDexhibitrelatively high hole mobility up to 1.4 cm2V–1s–1with high on/off ratio up to 106. In comparison, the hole mobility of OFETs with BFBPD(0.14 cm2V–1s–1) is relatively low, because of the poor thin-film morphology andlow molecular ordering, even after annealing. Thin-film morphologicaland XRD studies were carried out to understand the variation of holemobilities after annealing at different temperatures. The presentstudies clearly demonstrate the potentials of BPDthatis planar and polar as the electron-acceptor moiety to build D-A moleculesfor organic semiconductors with good performance. [ABSTRACT FROM AUTHOR]