Organic-based Devices Research Articles

Sn-Doping-Induced Biphasic Structure Advances Ductile Ag2S-Based Thermoelectrics.

Due to its inherent ductility, Ag2S shows promise as a flexible thermoelectric material for harnessing waste heat from diverse sources. However, its thermoelectric performance remains subpar, and existing enhancement strategies often compromise its ductility. In this study, a novel Sn-doping-induced biphasic structuring approach is introduced to synergistically control electron and phonon transport. Specifically, Sn-doping is incorporated into Ag2S0.7Se0.3 to form a biphasic composition comprising (Ag, Sn)2S0.7Se0.3 as the primary phase and Ag2S0.7Se0.3 as the secondary phase. This biphasic configuration achieves a competitive figure-of-merit ZT of 0.42 at 343 K while retaining exceptional ductility, exceeding 90%. The dominant (Ag, Sn)2S0.7Se0.3 phase bolsters the initially low carrier concentration, with interfacial boundaries between the phases effectively mitigating carrier scattering and promoting carrier mobility. Consequently, the optimized power factor reaches 5 µW cm-1 K-2 at 343 K. Additionally, the formation of the biphasic structure induces diverse micro/nano defects, suppressing lattice thermal conductivity to a commendable 0.18Wm-1K-1, thereby achieving optimized thermoelectric performance. As a result, a four-leg in-plane flexible thermoelectric device is fabricated, exhibiting a maximum power density of ≈49 µW cm-2 under the temperature difference of 30 K, much higher than that of organic-based flexible thermoelectric devices.

Direct-Written Silver Electrodes for All-Solution-Processed Low-Voltage Organic Thin Film Transistors Towards Flexible Electronics Applications

Recent progress inprinted electronics has offered the possibility of fabricatingvarious organic-based electronic devices,such as organic light-emitting diodes (OLEDs) and organic thin film transistors (OTFTs).As one of the important deposition methods inprinted electronics, an inkjet printing technique offers the deposition of solution-processable materials onto a variety of substrates using simpler fabrication steps at lower processing temperatures, which is suitable for flexible electronic applications. Despite being the leading choice in OTFT fabrication,the clogging issues that frequently occurred at the printhead nozzle havenot only limitedthe material selection but also restrained the efforts to bring organic electronic devices to the market. Apart from that, although remarkable progress has been made to enhance the performance of the OTFT, the high operating voltage resulting from the low gate capacitance density of the inorganic oxide-based dielectric layer remains a critical limitation that hinders the practical application of the OTFT. Hence, in this paper, we propose a simple solution-based method to develop a low-voltageOTFT. This work utilized a direct-write printing technique to print silver source/drain and gate electrodes incorporated into a bottomgate bottom contact OTFT structure, a spin-coating deposition method to deposit both small molecule TIPS-pentacene organic semiconducting layer and high-kPVA dielectric layer. Notably, the proposed OTFT achieved a micrometre channel length with a saturation mobility of 4.49 × 10-1cm2/Vs, a threshold voltage of -1.5V, an on/off current ratio of 108, and a subthreshold swing of 66.8mV/dec whilethe overall fabrication temperature and operating voltage arekept below 150 °Cand -15 V, respectively.The direct ink writing technology incorporated into the high-kdielectric layer provides a new strategy to fabricate organic-related components,particularly the OFTFs at lower manufacturing cost and temperature towardsflexible and low-operating voltage electronic devices.

A numerical simulation and analysis of chalcogenide BaZrS3-based perovskite solar cells utilizing different hole transport materials

Recently, barium zirconium sulfide (BaZrS3) chalcogenide perovskite (CP) material has attracted much attention in the photovoltaic community because of its excellent light harvesting ability, stability, and nontoxicity. BaZrS3 has shown great potential in becoming the best alternative to hybrid halide perovskites. Herein, we have numerically simulated and optimized the performance of a device with the general architecture FTO/WS2/BaZrS3/HTL/Au, using SCAPS-1D (version 3.3.07) software. In this general device, inorganic CuSCN, Cu2O and organic poly(3-hexylthiophene) (P3HT) were inserted, and performance was evaluated as hole transport layer (HTL) materials. Moreover, the influence of various parameters on the device, such as the effect of changing the absorber defect density, varying the operation temperature, and using different metal back contacts, were examined. The best HTL material was organic P3HT, and it exhibited a power conversion efficiency (PCE) of 13.86 %, with a Fill factor (FF) of 11.97 %, open circuit voltage (Voc) of 6.58 V, and current density (Jsc) of 17.59 mA cm−2. The other tested inorganic CuSCN and Cu2O HTL showed a PCE of 13.83 and 13.70 %, respectively. For all the devices, the optimum density of defects was kept at 1.0 × 1015 cm−2. It was established that the P3HT-based device can operate and be stable between 240–––340 K temperature window, while devices with CuSCN and Cu2O can work between 280 – 400 K temperature range. Thus, the CuSCN- and Cu2O-based devices were more stable because they could form a more compact structure that can withstand relatively higher operation temperatures than organic-based devices with P3HT as HTL. Finally, it was established that relatively cheaper metals such as Pt, Ni, and Pd can be suitable alternatives to expensive gold metal back contact. It is expected that this work would shed additional light on the utilisation of BaZrS3 as a promising absorber material in the actual manufacturing of solar cells for clean energy production.

Utilizing Metal Oxide Thin Films for Device Engineering of Solution-Processed Organic Multi-Junction Solar Cells

Electron and hole transporting layers play a major role in high-performance and stable organic-based optoelectronic devices. This paper demonstrates detailed device engineering of multi-junction organic photovoltaics built on two different metal oxide-based electron and hole transport (buffer) layers prepared by thermal or solution-processed methods. The main focus is on the device processing parameters as well as practical details of preparation of buffer layers to give the research community a clear, step-by-step recipe to successfully replicate and build series and parallel connected multi-junction solution-based organic solar cells for their needs. Here, the recipes and deposition conditions of two metal oxide buffer layers are presented in detail, based on basic commercially available materials and tools, to achieve well-engineered tandem (multi-junction) solution-processed organic solar cells. The buffer layers have appropriate energy levels for electrical selectivity of anode and cathode electrodes, and they are highly stable and chemically compatible with processing of solution-based polymer solar cells. To demonstrate the engineering steps of multi-junction devices, the PCE10:PC70BM blend is used as the active layer for all subcells. Then, to improve the power conversion efficiency of the single-junction photovoltaic device, PCE10:PC70BM blend is used in combination with DPPx:PC70BM with different absorption spectra for bottom and top subcell active layers. An optimized series tandem device with 10.6% power conversion efficiency is demonstrated. Generally, the device structures reported here can also be used for other types of optoelectronic devices, such as light emitting diodes and photodetectors.

Diamino-Substituted Quinones as Cathodes for Lithium-Ion Batteries.

This study introduces a sustainable approach to designing organic cathode materials (OCMs) for lithium-ion batteries as a potential replacement for traditional metal-based electrodes. Utilizing green synthetic methodologies, we synthesized and characterized five distinct quinone derivatives and investigated their electrochemical attributes within Li-ion battery architectures. Notably, the observed specific capacities were lower than the theoretical predictions, suggesting limitations in achieving efficient redox reactions in a coin-cell configuration. Among the quinone derivatives studied, one variant derived from natural vanillin showed superior cycle stability, maintaining 58% capacity retention over 95 charge-discharge cycles, and achieving a Coulombic efficiency of 90%. Importantly, we discovered that the commonly used Super-P conductive carbon did not yield any measurable battery performance; instead, these quinones necessitated the incorporation of graphene nanoplatelets as the conductive matrix. Through a facile one-step synthesis in ethanol or water, we have demonstrated a viable synthetic route for producing OCMs, albeit with moderate performances, which have attempted to address common concerns of high solubility and poor redox reactivity of previous OCMs, thereby offering a sustainable pathway for the development of organic-based energy storage devices.

Tailoring the optoelectronic properties of nanocrystalline β-H2Pc films via thermal annealing: Structural, morphological, and optical analyses

The present study extensively investigates the optical and structural properties of β-H2Pc thin films before and after annealing at temperatures of 373, 423, 473, 523, and 573 K/1 h, enabling the design of efficient organic-based devices. The mean crystallite size was calculated from XRD and found to be 8.5 nm at 300 K, which increased as the annealing temperature increased, confirming the crystallinity improvement upon annealing. In addition, the SEM images revealed that the grain size increased with increasing annealing temperature. The FTIR results confirmed the high thermal and chemical stability upon annealing. Furthermore, increasing the annealing temperature leads to a decrease in the transmittance spectrum and an increase in the reflectance spectrum. The results revealed a decrease in the optical band gap of β-H2Pc films from 1.472 eV to 1.406 eV for the onset gap and from 2.44 to about 2.21 eV for the fundamental gap with increasing annealing temperature to approximately 573 K. Moreover, the nonlinear optical parameters show an increase with higher thermal treatment temperatures. The annealing process has a significant impact on the optical and structural properties, leading to noticeable variations at specific annealing temperatures.

Metalloporphyrins on oxygen-passivated iron: Conformation and order beyond the first layer

On-surface metal porphyrins can undergo electronic and conformational changes that play a crucial role in determining the chemical reactivity of the molecular layer. Therefore, accessing those properties is pivotal for their implementation in organic-based devices. Here, by means of photoemission orbital tomography supported by density functional theory calculations, we investigate the electronic and geometrical structure of two metallated tetraphenyl porphyrins (MTPPs), namely ZnTPP and NiTPP, adsorbed on the oxygen-passivated Fe(100)-p(1 × 1)O surface. Both molecules weakly interact with the surface as no charge transfer is observed. In the case of ZnTPP, our data correspond to those of moderately distorted molecules whereas NiTPP exhibits a severe saddle-shape deformation. From additional experiments on NiTPP multilayer films, we conclude that this distortion is a consequence of the interaction with the substrate, as the NiTPP macrocycle of the second layer turns out to be flat. We further find that distortions in the MTPP macrocycle are accompanied by an increasing energy gap between the highest occupied molecular orbitals (HOMO and HOMO-1). Our results demonstrate that photoemission orbital tomography can simultaneously probe the energy level alignment, the azimuthal orientation, and the adsorption geometry of complex aromatic molecules even in the multilayer regime.

Visualization of molecular stacking using low-energy electron microscopy

The design of metal-organic interfaces with atomic precision enables the fabrication of highly efficient devices with tailored functionality. The possibility of fast and reliable analysis of molecular stacking order at the interface is of crucial importance, as the interfacial stacking order of molecules directly influences the quality and functionality of fabricated organic-based devices. Dark-field (DF) imaging using Low-Energy Electron Microscopy (LEEM) allows the visualization of areas with a specific structure or symmetry. However, distinguishing layers with different stacking orders featuring the same diffraction patterns becomes more complicated. Here we show that the top layer shift in organic molecular bilayers induces measurable differences in spot intensities of respective diffraction patterns that can be visualized in DF images. Scanning Tunneling Microscopy (STM) imaging of molecular bilayers allowed us to measure the shift directly and compare it with the diffraction data. We also provide a conceptual diffraction model based on the electron path differences, which qualitatively explains the observed phenomenon.

Schottky barrier height engineering on MoS2 field-effect transistors using a polymer surface modifier on a contact electrode

Two-dimensional (2D) materials are highly sought after for their superior semiconducting properties, making them promising candidates for next-generation electronic and optoelectronic devices. Transition-metal dichalcogenides (TMDCs), such as molybdenum disulfide (MoS2) and tungsten diselenide (WSe2), are promising alternative 2D materials. However, the devices based on these materials experience performance deterioration due to the formation of a Schottky barrier between metal contacts and semiconducting TMDCs. Here, we performed experiments to reduce the Schottky barrier height of MoS2 field-effect transistors (FETs) by lowering the work function (Фm = Evacuum − EF,metal) of the contact metal. We chose polyethylenimine (PEI), a polymer containing simple aliphatic amine groups (–NH2), as a surface modifier of the Au (ФAu = 5.10 eV) contact metal. PEI is a well-known surface modifier that lowers the work function of various conductors such as metals and conducting polymers. Such surface modifiers have thus far been utilized in organic-based devices, including organic light-emitting diodes, organic solar cells, and organic thin-film transistors. In this study, we used the simple PEI coating to tune the work function of the contact electrodes of MoS2 FETs. The proposed method is rapid, easy to implement under ambient conditions, and effectively reduces the Schottky barrier height. We expect this simple and effective method to be widely used in large-area electronics and optoelectronics due to its numerous advantages.

Are Accelerated and Enhanced Wave Function Methods Accurate to Compute Static Linear and Nonlinear Optical Properties?

Key components of organic-based electro-optic devices are challenging to design or optimize because they exhibit nonlinear optical responses, which are difficult to model or rationalize. Computational chemistry furnishes the tools to investigate extensive collections of molecules in the quest for target compounds. Among the electronic structure methods that provide static nonlinear optical properties (SNLOPs), density functional approximations (DFAs) are often preferred because of their low cost/accuracy ratio. However, the accuracy of the SNLOPs critically depends on the amount of exact exchange and electron correlation included in the DFA, precluding the reliable calculation of many molecular systems. In this scenario, wave function methods such as MP2, CCSD, and CCSD(T) constitute a reliable alternative to compute SNLOPs. Unfortunately, the computational cost of these methods significantly restricts the size of molecules to study, a limitation that hampers the identification of molecules with significant nonlinear optical responses. This paper analyzes various flavors and alternatives to MP2, CCSD, and CCSD(T) methods that either drastically reduce the computational cost or improve their performance but were scarcely and unsystematically employed to compute SNLOPs. In particular, we have tested RI-MP2, RIJK-MP2, RIJCOSX-MP2 (with GridX2 and GridX4 setups), LMP2, SCS-MP2, SOS-MP2, DLPNO-MP2, LNO-CCSD, LNO-CCSD(T), DLPNO-CCSD, DLPNO-CCSD(T0), and DLPNO-CCSD(T1). Our results indicate that all these methods can be safely employed to calculate the dipole moment and the polarizability with average relative errors below 5% with respect to CCSD(T). On the other hand, the calculation of higher-order properties represents a challenge for LNO and DLPNO methods, which present severe numerical instabilities in computing the single-point field-dependent energies. RI-MP2, RIJK-MP2, or RIJCOSX-MP2 are cost-effective methods to compute first and second hyperpolarizabilities with a marginal average error with respect to canonical MP2 (up to 5% for β and up to 11% for γ). More accurate hyperpolarizabilities can be obtained with DLPNO-CCSD(T1); however, this method cannot be employed to obtain reliable second hyperpolarizabilities. These results open the way to obtain accurate nonlinear optical properties at a computational cost that can compete with current DFAs.

Long-Term Cycling Stability of Porphyrin Electrode for Li/Na Charge Storage at High Temperature.

Bipolar redox organic compounds have been considered as potential next-generation electrode materials due to their sustainability, low cost and tunable structure. However, their development is still limited by the poor cycling stability and low energy density ascribed to high dissolution during cycling and the low conductivity of organic molecules. Herein, porphyrin-based bipolar organics of [5,10,15,20-tetrathienylporphinato] MII (M=2 H, Cu (CuTTP)) are proposed as new stable organic electrodes. Enhanced cycling stability is obtained by a temperature-induced in situ polymerization strategy of porphyrin molecules. The resulting polymer exhibits excellent cycling stability up to 10 00 cycles even at a high current density (1000 mA g-1 ) in organic lithium-/sodium-based charge storage devices at 50 °C. In a symmetrical cell using CuTTP as both cathode and anode material a discharge capacity of 72 mAh g-1 is achieved after 600 cycles at 1000 mA g-1 . This strategy would offer a new approach to developing stable energy storage bipolar materials in organic-based devices at high temperature.

UV and aging effect on the degradation of PEDOT:PSS/nSi films for Hybrid Silicon solar cells

Poly(3,4-ethylene-dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is one of the most successful conductive polymers, key component in different organic-based devices including silicon Hybrid Solar Cells (HSCs). However, there is limited information so far about the stability of this polymer under operation scenarios similar to those employed during performance, including UV irradiation or storage time. In this work, PEDOT:PSS thin layers have been spin coated onto silicon substrates, and their stability has been analysed under different conditions. Firstly, the influence under laser irradiation has been studied by Raman spectroscopy using both an UV-laser of 325 nm and a VIS-laser of 633 nm, with variable irradiation intensities and exposure time. Secondly, the effect of the removal of the native silicon oxide layer on the silicon substrate on the stability and passivation performance of the PEDOT:PSS has been analysed. Lastly, and closely related to its application in HSCs, the photoluminescence recombination has been analysed over storage time for 2 months to evaluate their real implementation as long-lasting solar cells.

Boosting hole migration through oxygen species–functionalized graphene interlayer for organic-based optoelectronic devices with enhanced efficiency and long-term durability

Poly(3,4-ethylenedioxythiophene polystyrene sulfonate) (PEDOT:PSS) has attracted attention for use in organic optoelectronic devices because of its efficient hole-migration characteristics, tunable energy, and low cost. However, the acidic and hygroscopic nature of PSS species limit the device performance significantly. Herein we present an efficient approach for improving the hole-transport properties and long-term stability of devices by conformally incorporating O-species functionalized graphene (O-Gr) as hole interfacial layer on the PEDOT:PSS surface. In our density functional theory calculation, the oxygen-containing vacancy in O-Gr can efficiently accept holes and transport them by suppressing the charge recombination. The introduction of O-Gr interlayer promotes efficient charge migration, improves the film properties of the upper layer, and suppresses the leakage current in organic optoelectronic devices, including organic photovoltaics (OPVs) and organic light-emitting diodes (OLEDs). Consequently, an increase of 11% in short-circuit current density (Jsc) is observed in the O-Gr-incorporated OPV in comparing with pristine device. As for the OLEDs, the employ of O-Gr considerably improves the maximum quantum efficiency (27%) and current efficiency (Cd/A) (29%) of device. Tuning hole extraction via the introduction of interfacial O-Gr can be a promising strategy for the advancement of PEDOT:PSS-based organic optoelectronics.

2D-Layered Structure WS2 Nanosheets with Improved Electrochromism for Organic-Based Device

A solid-state electrochromic device is assembled via polythiophene (P3HT) and tungsten disulfide (WS2)-introduced ethyl viologen (EV) layers. The WS2 nanosheets are prepared via a facile one-step hydrothermal technique and investigated via scanning electron microscopy, X-ray diffractometer and Raman spectra. The device exhibits the enhanced electrochromic properties, such as response time (0.9 s/1.3 s), cyclic stability (1000 cycles), coloration efficiency (410 cm2 C−1), and the reversible color switching from pink to blue at the small applied potential (±1.6 V). This indicates that WS2 with graphene-like 2D-layered nanostructure has the weak van der Waals force between the layers, which can store and transfer electrical charges between the films and electrolytes, thus improving the carrier mobility, which is crucial for improving the properties of electrochromic device. In addition, the introduction of WS2 promoted the device to become one of the most efficient polythiophene-viologen based devices. Therefore, this work provides a basis for the development of new electrochromic devices as the alternatives to the graphene-based devices.

Effect of oligothiophene spacer length on photogenerated charge transfer from perylene diimide to boron-doped diamond electrodes

Organic-based photovoltaic devices emerged as a complementary technology to silicon solar cells with specific advantages in terms of cost, ease of deployment, semi-transparency, and performance under low and diffuse light conditions. In this work, thin-film boron-doped diamond (B:NCD) electrodes are employed for their useful optical, electronic, and chemical properties, as well as stability and environmental safety. A set of oligothiophene perylene diimide (nT-PDI) donor-acceptor chromophores is designed and synthesized in order to investigate the influence of the oligothiophene spacer length when the nT-PDI molecule is attached to a B:NCD electrode. The chromophores are anchored to the diamond surface via diazonium grafting followed by Sonogashira cross-coupling. X-ray photoelectron spectroscopy shows that the surface coverage decreases with increasing oligothiophene length. Density functional theory (DFT/TDDFT) calculations reveal the upright nT-PDI orientation and the most efficient photogenerated charge separation and injection to diamond for elongated oligothiophene chains (8T-PDI). Yet, the maximum photovoltage is obtained for an intermediate oligothiophene length (3T-PDI), providing an optimum between decreasing transport efficiency and increasing efficiency of charge separation and reduced recombination with increasing oligothiophene length. Holes transferred from nT-PDI to diamond persist there even after the illumination is switched off. Such features may be beneficial for application in solar cells. • Variable donor-acceptor chromophore/diamond system designed in-silico and fabricated. • Oligothiophene donor length adjusts valence band and charge transport with diamond. • Intermediate oligothiophene length (3 units) yields the maximum photovoltage. • Up to 0.87 electron per molecule transferred to diamond across 44 Å under excitation.

Aerosol Jet Printed Organic Memristive Microdevices Based on a Chitosan:PANI Composite Conductive Channel

In this study we show a chitosan:polyaniline (CPA)-based ink, responding to eco-biofriendly criteria, specifically developed for the manufacturing of the first organic memristive device (OMD) with an aerosol jet printed conductive channel. Our contribution is in the context of bioelectronics, where there is an increasing interest in emulating neuromorphic functions. In this framework, memristive devices and systems have been shown to be well suited. In particular organic-based devices are envisaged as very promising in some applications, such as brain–machine interfacing, owing to specific properties of organics (e.g., biocompatibility, mixed ionic–electronic conduction). On the other hand, the research activities on flexible organic (bio)electronic devices and direct writing (DW) noncontact techniques increasingly overlap in the effort of achieving reliable applications benefiting from the rapid prototyping to accomplish a fast device optimization. In this context, ink-based techniques, such as aerosol jet printing (AJP), although particularly well suited to implement 3D-printed electronics due to advantages it offers in terms of a wide set of allowed printable materials, still require research efforts aimed at conferring printability to the desired precursors. The developed CPA composite was characterized by FTIR, DLS, and MALDI-TOF techniques, while the related aerosol jet printed films were studied by SEM and profilometry. Taking advantage of the intrinsic and stable electrical conductivity of CPA films, which do not necessarily require any acidic treatment to promote a sustained charge carrier conduction, 10 μm short-channel OMDs were hence manufactured by interfacing the printed CPA layers with a solid polyelectrolyte (SPE). We accordingly demonstrated prototypes of stable and best performing OMD devices with downscaled features, showing well-defined counterclockwise hysteresis/rectification and an enhanced durability. These properties pave the way to further improving performance, as well as to realizing a direct integration of the devices into hardware neural networks by in-line fabrication routes.

Organic bulk heterojunction enabled with nanocapsules of hydrate vanadium pentaoxide layer for high responsivity self-powered photodetector

This article demonstrates the fabrication of organic-based devices using a low-cost solution-processable technique. A blended heterojunction of chlorine substituted 2D-conjugated polymer PBDB-T-2Cl, and PC71BM supported nanocapsules hydrate vanadium penta oxides (HVO) as hole transport layer (HTL) based photodetector fabricated on an ITO coated glass substrate under ambient condition. The device forms an excellent organic junction diode with a good rectification ratio of ~200. The device has also shown excellent photodetection properties under photoconductive mode (at reverse bias) and zero bias for green light wavelength. A very high responsivity of ~6500 mA/W and high external quantum efficiency (EQE) of 1400% have been reported in the article. The proposed organic photodetector exhibits an excellent response and recovery time of ~30 and ~40 ms, respectively.

New Opportunities for Organic Semiconducting Polymers in Biomedical Applications

The life expectancy of humans has been significantly elevated due to advancements in medical knowledge and skills over the past few decades. Although a lot of knowledge and skills are disseminated to the general public, electronic devices that quantitatively diagnose one’s own body condition still require specialized semiconductor devices which are huge and not portable. In this regard, semiconductor materials that are lightweight and have low power consumption and high performance should be developed with low cost for mass production. Organic semiconductors are one of the promising materials in biomedical applications due to their functionalities, solution-processability and excellent mechanical properties in terms of flexibility. In this review, we discuss organic semiconductor materials that are widely utilized in biomedical devices. Some advantageous and unique properties of organic semiconductors compared to inorganic semiconductors are reviewed. By critically assessing the fabrication process and device structures in organic-based biomedical devices, the potential merits and future aspects of the organic biomedical devices are pinpointed compared to inorganic devices.

Charge transport in cove-type graphene nanoribbons: The role of quasiparticles

Previous reports indicate that cove-type graphene nanoribbons (CGNR) may present high intrinsic charge mobility of almost 15,000 cm2/Vs. Still, with experimental estimates varying from 150 to 15,000 cm2/Vs. Typically, theoretical mobilities are obtained from methods such as the Drude-Smith model, which tends to neglect the electron-phonon coupling mechanism, or the Boltzmann transport equation, that considers only acoustic phonons. As such, more thorough approaches are needed. In this work, we simulated charge transport in 4-CGNR by explicitly contemplating the lattice collective behavior. The nanoribbon is simulated by a two-dimensional Su-Schrieffer-Heeger (SSH) tight-binding model with electron-phonon coupling and considering all phonon modes. Results show the rise of two quasiparticles: polaron and bipolaron. We probed their dynamical properties by including the presence of an external electric field. Findings indicate that each carrier has a characteristic transport regime that is deeply related to phonon collision interactions. Model derived mobilities for polarons and bipolarons reach up to 18,000 cm2/Vs and 1500 cm2/Vs, respectively. Furthermore, calculations reveal the carriers to be highly efficient charge transporters, with a field independent low effective mass and notable mobility, delivering a better performance than other narrow GNRs. All presented features place the CGNR as a potential base material of future high-quality organic-based optoelectronic devices. The work also contributes to the theoretical understanding of transport physics in highly confined materials.

Unveiling the robustness of porphyrin crystalline nanowires toward aggressive chemicals

One of the keys for the development of porphyrin-based devices implies that their functionality must be robust and stable against external environmental factors. While the research has been mostly focused on the supramolecular aggregate interactions with target chemicals, the robustness of organic nanostructures in contaminating and even aggressive environments has not been diffusely investigated yet. The results here presented show that crystalline nanowires of meso-tetraphenyl porphyrin (H2TPP) and meso-tetraphenyl porphyrin-Zn(II) (ZnTPP) are insensitive to the exposure to a series of purposely chosen analytes (alcohols, alkanes and amines). Our finding suggests possible applications of the nanowires in organic-based devices (overwhelming the well-known intrinsic weakness of organic electronics), related to material stability through an appropriate material design and the opportunity offered by organic epitaxy.