Project description:Currently, studies on organic two-dimensional (2D) materials with special optic-electronic properties are attracting great research interest. However, 2D organic systems possessing promising electrical transport properties are still rare. Here a highly crystalline thin film of a copper coordination polymer, Cu-BHT (BHT=benzenehexathiol), is prepared via a liquid-liquid interface reaction between BHT/dichloromethane and copper(II) nitrate/H2O. The morphology and structure characterization reveal that this film is piled up by nanosheets of 2D lattice of [Cu3(C6S6)]n, which is further verified by quantum simulation. Four-probe measurements show that the room temperature conductivity of this material can reach up to 1,580?S?cm(-1), which is the highest value ever reported for coordination polymers. Meanwhile, it displays ambipolar charge transport behaviour and extremely high electron and hole mobilities (99?cm(2?)V(-1?)s(-1) for holes and 116?cm(2?)V(-1?)s(-1) for electrons) under field-effect modulation.
Project description:Two-dimensional (2D) ferroelectric transistors hold unique properties and positions, especially talking about low-power memories, in-memory computing, and multifunctional logic devices. To achieve better functions, appropriate design of new device structures and material combinations is necessary. We present an asymmetric 2D heterostructure integrating MoTe2, h-BN, and CuInP2S6 as a ferroelectric transistor, which exhibits an unusual property of anti-ambipolar transport characteristic under both positive and negative drain biases. Our results demonstrate that the anti-ambipolar behavior can be modulated by external electric field, achieving a peak-to-valley ratio up to 103. We also provide a comprehensive explanation for the occurrence and modulation of the anti-ambipolar peak based on a model describing linked lateral-and-vertical charge behaviors. Our findings provide insights for designing and constructing anti-ambipolar transistors and other 2D devices with significant potential for future applications. Supplementary Information The online version contains supplementary material available at 10.1186/s11671-023-03860-2.
Project description:Few semiconducting polymers are known that possess more than one semi-crystalline structure. Guidelines for rationalizing or creating polymorphism in these materials do not exist. Two different semi-crystalline polymorphs, β 1 and β 2, and an amorphous α phase have recently been identified for alternating diketopyrrolopyrrole-quaterthiophene copolymers (PDPP4T). The polymorphs differ structurally by the π-π stacking distance, and electronically by the optical bandgap and charge carrier mobility. Here we investigate the corresponding terthiophene (PDPP3T) derivatives, to study the effect of the relative orientation of adjacent DPP units on the polymorphism. In PDPP3T, the relative orientation of DPP units alternates along the chain, while in PDPP4T it is constant. We show that the two polymorphs, β 1 and β 2, can also be generated for a PDPP3T polymer in solution and thin film. Interestingly, compared to PDPP4T, more solvents can induce the two distinct semi-crystalline polymorphs for PDPP3T via a β 1 → α → β 2 polymorphic transition.
Project description:Chiral diketopyrrolopyrrole (DPP)-helicene polymers were synthesized to develop efficient red circularly polarized (CP) light emitters. These original chiral dyes display intense electronic circular dichroism (ECD) and CP luminescence (CPL) in the far-red spectral region owing to the presence of excitonic coupling between achiral DPPs within the chiral environment of the polymeric structure. This work affords an interesting example illustrating the potential of π-conjugated helical polymers for chiral optoelectronic applications.
Project description:Diketopyrrolopyrrole-based semiconducting polymer nanoparticles with high photostability and strong photoacoustic brightness are designed and synthesized, which results in 5.3-fold photoacoustic signal enhancement in tumor xenografts after systemic administration.
Project description:Ambipolar polymer semiconductors are potentially serviceable for logic circuits, light-emitting field-effect transistors (LFETs) and polymer solar cells (PSCs). Although several high-performance ambipolar polymers have been developed, their optoelectronic devices are generally processed from toxic chlorinated solvents. To achieve the commercial applications of organic FETs (OFETs), the polymers should be processed from nonchlorinated solvents, instead of chlorinated solvents. However, most conjugated polymers show poor solubility in nonchlorinated solvents. It is of great importance to develop ambipolar polymers that can be processed from nonchlorinated solvents. Here, we develop a nonchlorinated solvent processed polymer named poly[7-fluoro-N, N'-di(4-decyltetradecyl)-7'-azaisoindigo-6',6″-(thieno[3,2-b]thiophene-2,5-diyl)-7‴-fluoro-N″, N‴-di(4-decyltetradecyl)-7″-azaisoindigo-6,6‴-([2,2″-bithiophene]-5,5″-diyl)] (PITTI-BT) by designing a monomer with a large molar mass. The polymer displays good solubility in p-xylene (PX). Well-aligned films of PITTI-BT are achieved by an off-center spin-coating (SC) method. Based on the high-quality films, the OFETs fabricated from PX solution achieve record ambipolar performance with hole and electron mobilities of 3.06 and 2.81 cm2 V-1 s-1, respectively. The combination of nonchlorinated solvents and good alignment process offers an effective and eco-friendly approach to obtain high-performance ambipolar transistors.
Project description:The possibility to selectively modulate the charge carrier transport in semiconducting materials is extremely challenging for the development of high performance and low-power consuming logic circuits. Systematical control over the polarity (electrons and holes) in transistor based on solution processed layer by layer polymer/graphene oxide hybrid system has been demonstrated. The conversion degree of the polarity is well controlled and reversible by trapping the opposite carriers. Basically, an electron device is switched to be a hole only device or vice versa. Finally, a hybrid layer ambipolar inverter is demonstrated in which almost no leakage of opposite carrier is found. This hybrid material has wide range of applications in planar p-n junctions and logic circuits for high-throughput manufacturing of printed electronic circuits.
Project description:Aligned films of a semiconducting DPP-based copolymer exhibit highly anisotropic charge transport with a band-like temperature dependence along the alignment direction and hole mobilities of up to 6.7 cm(2) V(-1) s(-1) . X-ray diffraction measurements reveal an exceptional degree of in-plane alignment, high crystallinity, and a dominant face-on orientation of the polymer backbones. The surprising charge-transport properties are interpreted in a tie-chain model consistent with anisotropic activation energies.
Project description:Flexible memory cell array based on high mobility donor-acceptor diketopyrrolopyrrole polymer has been demonstrated. The memory cell exhibits low read voltage, high cell-to-cell uniformity and good mechanical flexibility, and has reliable retention and endurance memory performance. The electrical properties of the memory devices are systematically investigated and modeled. Our results suggest that the polymer blends provide an important step towards high-density flexible nonvolatile memory devices.
Project description:Polythiophene, as a class of potential electron donor units, is widely used in organic electronics such as transistors. In this work, a novel polymeric material, PDPPTT-FT, was prepared by incorporating the electron acceptor unit into the polythiophene system. The incorporation of the DPP molecule assists in improving the solubility of the material and provides a convenient method for the preparation of field effect transistors via subsequent solution processing. The introduction of fluorine atoms forms a good intramolecular conformational lock, and theoretical calculations show that the structure displays excellent co-planarity and regularity. Grazing incidence wide-angle X-ray (GIWAXS) results indicate that the PDPPTT-FT is highly crystalline, which facilitates carrier migration within and between polymer chains. The hole mobility of this π-conjugated material is as high as 0.30 cm2 V-1 s-1 in organic transistor measurements, demonstrating the great potential of this polymer material in the field of optoelectronics.