Porphyrin-fused graphene nanoribbons
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2024-03-08 |
| Journal | Nature Chemistry |
| Authors | Qiang Chen, Alessandro Lodi, Heng Zhang, Alex Gee, Hai I. Wang |
| Institutions | University of Nottingham, Soochow University |
| Citations | 52 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Porphyrin-Fused Graphene Nanoribbons (PGNRs)
Section titled âTechnical Documentation & Analysis: Porphyrin-Fused Graphene Nanoribbons (PGNRs)âExecutive Summary
Section titled âExecutive SummaryâThis research demonstrates a scalable solution-phase synthesis of Porphyrin-fused Graphene Nanoribbons (PGNRs), establishing a new class of materials highly promising for advanced molecular electronics, spintronics, and quantum computing.
- Material Achievement: Successful solution-phase synthesis of long PGNR chains (average length 85 nm) via Yamamoto polymerization followed by cyclodehydrogenation.
- High Mobility: Contact-free ultrafast optical-pump terahertz-probe (OPTP) spectroscopy measured an exceptional local charge mobility of 450 ± 60 cm2 V-1 s-1, significantly higher than most pure carbon GNRs.
- Electronic Performance: PGNRs were integrated into ambipolar field-effect transistors (FETs) exhibiting high room-temperature mobilities (up to 40 cm2 V-1 s-1) and excellent gate control (SS â 400 mV dec-1).
- Quantum Potential: Single-electron transistors fabricated using PGNRs displayed clear Coulomb diamonds at 25 mK, confirming their potential for low-power quantum electronics.
- Optical Properties: The material exhibits a narrow optical bandgap of approximately 1.0 eV, making it suitable for near-infrared (NIR) applications.
- Spintronics Pathway: The incorporation of Ni(II) metalloporphyrins provides a direct avenue for tuning electrical and magnetic properties, opening opportunities for spintronic and memory device development.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| PGNR Average Length | 85 | nm | Weight-average, N â 34 repeat units |
| Optical Bandgap (Eg) | 1.0 | eV | Estimated from absorption onset (1,200 nm) |
| Local Charge Mobility (”) | 450 ± 60 | cm2 V-1 s-1 | Measured by Ultrafast OPTP Spectroscopy |
| DC Limit Mobility (”dc) | 32 ± 4 | cm2 V-1 s-1 | Estimated considering backscattering |
| Linear Field-Effect Mobility (”lin) | 40 ± 5 | cm2 V-1 s-1 | Room temperature FET operation |
| Saturation Field-Effect Mobility (”sat) | 4 ± 1 | cm2 V-1 s-1 | Room temperature FET operation |
| ON/OFF Current Ratio | â 103 | N/A | Ambipolar FETs at VSD = 0.1 V |
| Carrier Momentum Scattering Time (Ï) | 54 ± 7 | fs | Inferred from Drude-Smith model |
| Single-Electron Transistor Temp | 25 | mK | Observation of Coulomb diamonds |
| Dielectric Stack Used | 300 nm SiO2 / 10 nm HfO2 | N/A | Substrate platform for device fabrication |
Key Methodologies
Section titled âKey MethodologiesâThe synthesis and characterization relied on precise chemical control and advanced spectroscopic techniques.
- Monomer Design: Dichloroporphyrin monomer 2b was designed with bulky sidechains (dodecylphenyl groups) and Ni(II) insertion to ensure high solubility and prevent core protonation during planarization.
- Polymerization: High-molecular-weight polyphenylene chains (PPb) were synthesized via Yamamoto polymerization of monomer 2b using Ni(COD)2 in THF solvent (93% yield).
- Planarization: Subsequent cyclodehydrogenation of PPb was achieved using DDQ/TfOH in DCM, yielding the final Porphyrin-fused Graphene Nanoribbon (PGNRb) in 94% yield.
- Structural Verification: The structure and complete dehydrogenation were confirmed using solid-state CP-MAS 1H NMR, UV-vis-NIR absorption, Raman, and X-ray photoelectron spectroscopy (XPS).
- Charge Transport Measurement: Local charge dynamics were assessed using contact-free ultrafast optical-pump terahertz-probe (OPTP) spectroscopy, providing insight into the intrinsic mobility before device integration.
- Device Fabrication: Single PGNR strands were drop-cast onto electro-burnt graphene nanogaps (3-7 nm width) fabricated on a Si/SiO2 substrate with a 10 nm HfO2 dielectric layer.
- Quantum Transport: Single-electron transistor characteristics were mapped at 25 mK, revealing periodic Coulomb diamonds and regions of negative differential conductance (NDC).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe successful replication and scaling of high-performance molecular electronic devices, particularly those operating at high frequencies (THz) or cryogenic temperatures (25 mK), require substrates with exceptional thermal, electrical, and surface properties. 6CCVDâs MPCVD diamond materials are ideally suited to enhance and stabilize this research.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate or extend this research into commercial or high-power applications, 6CCVD recommends the following materials:
| Material Recommendation | Specification | Rationale for PGNR Research |
|---|---|---|
| Electronic Grade Single Crystal Diamond (SCD) | SCD Plates (0.1”m - 500”m thickness), Ra < 1 nm polishing. | Superior Thermal Management: Diamond offers the highest known thermal conductivity, critical for managing heat in high-density FET arrays or during high-power THz measurements. |
| High-Purity Polycrystalline Diamond (PCD) | Wafers up to 125 mm diameter, Ra < 5 nm polishing. | Scalability: Provides large-area, high-quality substrates necessary for scaling up the solution-processed PGNR devices. |
| Boron-Doped Diamond (BDD) | SCD or PCD substrates (up to 10 mm thick). | Advanced Gate Electrode: BDD can replace the doped Si gate, offering a chemically inert, highly conductive, and stable gate material, potentially reducing hysteresis observed in FETs. |
Customization Potential
Section titled âCustomization Potentialâ6CCVD provides the necessary engineering precision to optimize the substrate and electrode interfaces, which are critical for achieving the reported high charge mobilities.
- Ultra-Smooth Polishing: The performance of the atomically precise PGNRs is highly sensitive to surface roughness. 6CCVD guarantees ultra-smooth surfaces (Ra < 1 nm for SCD), ensuring minimal scattering and maximizing charge transport at the GNR/substrate interface.
- Custom Metalization Services: The paper utilized Ti/Pd/Au electrodes. 6CCVD offers in-house, high-precision deposition of all required contact metals (Au, Pt, Pd, Ti, W, Cu) to replicate or optimize the source/drain contacts for improved ohmic performance and stability.
- Custom Dimensions and Substrates: While the paper used standard Si wafers, 6CCVD can supply custom-sized SCD plates or large-area PCD wafers (up to 125 mm) to accommodate specific lithography requirements or large-scale device integration.
- Dielectric Integration: Diamond is compatible with high-k dielectrics like HfO2 (used in the paper). 6CCVD can assist in integrating these layers onto diamond substrates for enhanced gate control and reduced leakage current, surpassing the performance limits of Si/SiO2 platforms.
Engineering Support
Section titled âEngineering SupportâThe successful integration of PGNRs into single-molecule electronic devices requires deep expertise in material science and quantum transport phenomena.
- Application Expertise: 6CCVDâs in-house PhD team specializes in optimizing diamond material properties (surface termination, doping profiles, defect engineering) for similar single-molecule electronics, spintronics, and quantum computing projects.
- Cryogenic Stability: Diamond substrates offer superior stability and low thermal expansion at the millikelvin temperatures (25 mK) required for single-electron transistor mapping, ensuring reliable quantum measurements.
- Global Supply Chain: 6CCVD ensures reliable global shipping (DDU default, DDP available) of high-purity diamond materials, supporting international research efforts.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.