Jonas F. Poehls and R. Thomas Weitz · Advanced Functional Materials · 2026
Review how intrinsic transport mechanisms and extrinsic measurement factors shape reported electronic properties of MOFs and COFs, with emphasis on method selection, sample morphology, and device-relevant interpretation.
The review’s argument is preserved as a navigable set of section summaries.
Introduces conductivity, carrier density, mobility, band-like versus hopping transport, and practical signatures for assigning dominant transport regimes.
Relevance: Core · 3 · 2. Basis of Electronic Characterization · Figure 1
Discusses Hall measurements and field-effect transistors as carrier-density, mobility, polarity, and device-relevant tools, while warning about mixed ionic/electronic effects and interface traps.
Relevance: Core · 9 · 4.2.1. Hall Effect
Uses Cu3BHT, Cu3(HHTP)2, and WBDT to show that apparent conductivity can shift by orders of magnitude with sample form, geometry, contact quality, dopant distribution, and grain boundaries.
Relevance: Core · 16 · 5. Case Studies · Figure 5
Concludes that conductive MOF/COF progress requires standardised, multidimensional characterisation that connects intrinsic transport with macroscopic usable conductivity.
Relevance: Core · 19 · 6. Conclusion
Classifies framework conduction pathways and design trade-offs, including through-bond, through-space, extended conjugation, redox hopping, guest-mediated conduction, porosity, and stacking.
Relevance: Core · 4 · 3. Electrical Conductivity in Framework Materials
Frames MOFs and COFs as electronically tunable framework materials and states the review's focus on measurement choices rather than another broad survey of intrinsic mechanisms.
Relevance: Core · 2 · 1. Introduction
Surveys c-AFM, KPFM, STM, THz-TDS, TRMC, UV-vis-NIR, photoemission, TOF, impedance, and Seebeck methods as complementary probes of local, ultrafast, or device-scale transport.
Relevance: Core · 15 · 4.6. Technique Overview · Table 1
Explains two-probe, four-probe, and van der Pauw geometries and how pellet, thin-film, and single-crystal preparation affects conductivity interpretation.
Relevance: Core · 6 · 4.1. Two-Probe and Four-Probe Conductivity Measurements · Figure 2
Classification systems are attributed to this review and are not treated as a global material registry.
The review organises MOF/COF conduction mechanisms by whether charge travels through framework bonds, stacked aromatic units, conjugated backbones, redox sites, or guest species.
Categories: Through-bond conduction · Through-space pi-pi stacking · Extended pi-conjugation · Redox hopping · Guest-mediated conduction
4 · 3. Electrical Conductivity in Framework Materials
Macroscopic conductivity measurements are separated by whether contacts combine or separate current and voltage leads, and whether sheet resistance is extracted from a general geometry.
Categories: Two-probe · Four-probe · Van der Pauw
6 · 4.1.1. Choice of Contact Geometry · Figure 2
Table 1 classifies each method by the length scale probed, clarifying why different techniques should not be expected to produce the same apparent conductivity or mobility.
Categories: Device-scale · Channel-scale · Intragrain sub-micrometer · Nanoscale · Atomic-scale · Ensemble or reciprocal-space
15 · 4.6. Technique Overview · Table 1
The review repeatedly compares pellets, films, and single crystals because each samples different mixtures of intergrain and intragrain transport.
Categories: Pressed pellets · Thin films · Single crystals
8 · 4.1.2. Choice of Material Preparation · Figure 3
Figure 1 and the surrounding text describe transport as a continuum governed by crystallinity, domain size, trap density, and conjugation rather than a binary classification.
Categories: Band-like transport · Multiple trap and release · Hopping transport
3 · 2. Basis of Electronic Characterization · Figure 1c
The conclusion proposes a staged workflow that starts with standardised pellet screening and progresses to device, single-crystal, and local/spectroscopic correlation.
Categories: Initial screening · Device-relevant assessment · Intrinsic properties · Spectroscopic/local correlation
19 · 6. Conclusion
Review-defined families retain their representative materials and conduction descriptions.
Entirely organic, covalently linked frameworks in which pi-conjugated backbones and stacked layers can support charge transport.
Conduction: Transport is governed by covalent conjugation, interlayer pi-stacking, domain order, and dopant or guest effects.
Representative materials: DAAQ-TFP · WBDT · pyrene COFs · porphyrin COFs · phthalocyanine COFs
Nodes / linkers: none · imine · hydrazone · beta-ketoenamine · benzodithiophene · perylene diimide
5 · 3. Electrical Conductivity in Framework Materials
Metal nodes connected by organic linkers in periodic porous networks whose conductivity can arise from metal-ligand conjugation, redox activity, stacking, guests, or framework design.
Conduction: Electronic conduction can occur through metal-ligand bonds, stacked aromatic sheets, mixed-valence pathways, or guest-mediated charge transfer.
Representative materials: Fe2(DSBDC) · Ni3(HITP)2 · Cu3BHT · Cu3(HHTP)2 · MIL-53(Fe)
Nodes / linkers: Fe · Ni · Cu · Co · Mn · dithiolate linkers · hexaiminotriphenylene · benzenehexathiol · hexahydroxytriphenylene · semiquinone-type ligands
5 · 3. Electrical Conductivity in Framework Materials
Copper benzenehexathiol 2D MOF with sulfur-donor benzenehexathiol ligands forming a planar kagome-type lattice.
Conduction: Extended pi-d conjugation and mixed-valence Cu(I)/Cu(II) centres enable delocalised and narrow-band metallic behaviour, but pellet values are strongly affected by intergrain contacts.
Representative materials: Cu3BHT
Nodes / linkers: Cu · benzenehexathiol · dithiolate
16 · 5.1. Cu3BHT · Figure 5a-b
Layered copper hexahydroxytriphenylene MOF used to compare single-crystal, film, and pellet conductivity across measurement geometries.
Conduction: Theoretical symmetry suggests Dirac-like features, and recent optimised thin films show metallic charge transport within single-crystalline domains.
Representative materials: Cu3(HHTP)2 · CuHHTP
Nodes / linkers: Cu · hexahydroxytriphenylene
17 · 5.2. CuHHTP · Table 3
Layered 2D MOFs built from triphenylene-derived ligands coordinated to transition-metal nodes, used as examples of stacking- and anisotropy-dependent transport.
Conduction: Charge transport depends on in-plane conjugation, interlayer stacking, domain size, and anisotropy.
Representative materials: Ni3(HITP)2 · Cu3(HHTP)2
Nodes / linkers: Ni · Cu · 2,3,6,7,10,11-hexaiminotriphenylene · hexahydroxytriphenylene
4 · 3. Electrical Conductivity in Framework Materials
Imine-linked 2D COF with a Wurster-type node and benzodithiophene linker, compared in pellet and oriented-film formats under pristine and doped states.
Conduction: Conductivity varies with sample form and dopant; films favour in-plane transport, while pellets may benefit from dopant penetration and percolation.
Representative materials: WBDT
Nodes / linkers: none · Wurster-type node · benzodithiophene · imine linkage
17 · 5.3. WBDT · Table 4
Review-level synthesis principles remain separate from primary-study recipes.
Introduce conductive or redox-active guests or dopants to shift carrier density, alter the local dielectric environment, and create charge-transfer or percolation pathways.
Claimed effects: Can increase conductivity by orders of magnitude and reveal dopant-dependent carrier generation.
Controlling variables: dopant identity · guest loading · penetration depth · host-guest charge transfer · atmosphere and stability
Representative materials: MIL-53(Fe) · WBDT · Cu3(HHTP)2
Caveat: Doping can introduce time-dependent degradation, partial conductivity loss, or different pellet versus film percolation behaviour.
5 · 3. Electrical Conductivity in Framework Materials
Pair macroscopic conductivity with impedance, Hall/Seebeck, THz/TRMC, local probes, and spectroscopies to separate device-scale, intragrain, interface, and band-alignment contributions.
Claimed effects: Reduces misassignment of transport mechanisms and helps translate idealised local or ultrafast measurements to device-scale performance.
Controlling variables: measurement length scale · contact geometry · domain size · carrier density · environment · model assumptions
Representative materials: Cu3BHT · Cu3(HHTP)2 · WBDT
Caveat: The full workflow is demanding and may require collaboration across groups with different experimental expertise.
19 · 6. Conclusion
Prepare continuous MOF/COF films with controlled thickness, orientation, roughness, and electrode geometry for device-scale and in-plane transport measurements.
Claimed effects: Improves reproducibility and device integration, reduces interparticle contact resistance, and can access anisotropic in-plane conduction.
Controlling variables: film thickness · crystallographic orientation · domain size · surface roughness · channel geometry
Representative materials: Cu3(HHTP)2 thin films · WBDT oriented films · surface-mounted MOFs
Caveat: Thin-film values still depend strongly on continuity, channel length, contact quality, activation, and atmosphere.
7 · 4.1.2. Thin Films · Figure 3c-d
Select metal nodes and organic linkers so that orbital alignment, planarity, and accessible redox states support delocalisation or targeted redox hopping.
Claimed effects: Can tune conductivity, band structure, redox activity, and the balance between band-like and hopping behaviour.
Controlling variables: metal node identity · linker planarity · coordination geometry · orbital alignment · redox accessibility
Representative materials: Fe2(DSBDC) · Ni3(HITP)2 · Cu3BHT · Cu3(HHTP)2
Caveat: Designs that maximise orbital overlap can restrict building-block choice and are highly sensitive to defects and stacking.
5 · 3. Electrical Conductivity in Framework Materials
Use pressed-pellet conductivity as a first-pass screen only when pressure, dwell time, density, porosity, particle size, activation, contact material, and atmosphere are controlled and reported.
Claimed effects: Provides comparable screening values for powders and can identify promising systems for deeper film or crystal studies.
Controlling variables: pressing pressure · dwell time · pellet density · relative porosity · particle size distribution · contact material
Representative materials: Cu3BHT pellets · Cu3(HHTP)2 pellets · WBDT pellets
Caveat: Pellet compression can alter structure and pellet conductivity often mixes intragrain conduction with grain-boundary and particle-particle resistance.
7 · 4.1.2. Pressed Pellets · Figure 3a-b
These are the review authors’ synthesis, not newly measured results.
Band-like and hopping descriptions are limiting cases; real MOFs/COFs often contain both, with dominance set by domain size, trap density, conjugation, and structural order.
Evidence basis: review_reasoning
Caveat: No single crystallinity threshold is sufficient for classification.
4 · 2. Basis of Electronic Characterization · Figure 1c
Cu3BHT demonstrates that outstanding intrinsic or film properties, including metallic behaviour and superconductivity reports, can be masked in pellets by grain boundaries and intergrain contacts.
Evidence basis: multi_reference
Caveat: Table 2 compiles values from multiple studies with different sample histories and measurement geometries.
16 · 5.1. Cu3BHT · Table 2
Cu3(HHTP)2 values span from metallic thin-film behaviour to much lower pellet conductivities, demonstrating the influence of channel size, orientation, contact quality, and intergrain transport.
Evidence basis: multi_reference
Caveat: The review notes that films can appear higher than single crystals when geometry minimises contact or series resistance.
17 · 5.2. CuHHTP · Table 3
Hall measurements are powerful for carrier polarity, density, and mobility, but in MOFs/COFs can be compromised by small signals, mixed ionic/protonic contributions, anisotropy, and contact quality.
Evidence basis: review_reasoning
Caveat: Dry inert atmospheres and linear current-voltage checks are needed for reliable interpretation.
10 · 4.2.1. Hall Effect
Local probes such as c-AFM, KPFM, and STM are essential for spatial heterogeneity, work-function variation, and local electronic states, but are not direct substitutes for device-scale conductivity.
Evidence basis: multi_reference
Caveat: Surface sensitivity, tip artefacts, and sample requirements must be controlled.
11 · 4.3.1. Conductive Atomic Force Microscopy · Figure 4
For sensors, transistors, and other applications, macroscopic methods often better represent usable conductivity because they measure relevant length scales, even when local or spectroscopic probes reveal higher intrinsic potential.
Evidence basis: review_reasoning
Caveat: Macroscopic values still require standardised reporting to avoid systematic errors.
18 · 6. Conclusion
For conductive MOFs and COFs, measurement method can dominate the apparent property comparison; values for the same material can differ substantially by characterisation route.
Evidence basis: multi_reference
Caveat: The review is synthesising literature values, not remeasuring them.
2 · 1. Introduction
Pressed pellets are convenient for powders but can underestimate intrinsic conductivity because compression, porosity, random orientation, and interparticle junctions add extrinsic resistance.
Evidence basis: multi_reference
Caveat: Standardised pellet protocols retain screening value.
7 · 4.1.2. Pressed Pellets · Figure 3a-b
Single-crystal measurements best isolate anisotropic intragrain transport and should be used to validate mechanisms inferred from films and pellets.
Evidence basis: multi_reference
Caveat: Large, well-formed single crystals are difficult to obtain and contact alignment can introduce artefacts.
9 · 4.1.2. Single Crystals
Thin films offer better device relevance, reproducibility, and access to orientation-dependent transport than pellets, but still require careful control of morphology, contacts, and atmosphere.
Evidence basis: multi_reference
Caveat: Film measurements may over- or underrepresent device performance depending on channel geometry and continuity.
7 · 4.1.2. Thin Films
THz-TDS and TRMC provide contactless intragrain or ultrafast transport metrics that should usually be interpreted as upper bounds relative to DC device performance.
Evidence basis: multi_reference
Caveat: Translation to DC devices requires grain/domain metrics and effective-medium or resistor-network modelling.
13 · 4.4.1. Terahertz Spectroscopy · Figure 4g
Transport assignment should use complementary diagnostics such as temperature dependence, THz frequency response, Hall/Seebeck data, anisotropy, and coherence metrics.
Evidence basis: multi_reference
Caveat: Each diagnostic is sensitive to sample quality and contact or geometry assumptions.
4 · 2. Basis of Electronic Characterization
Two-probe conductivity can overestimate resistivity in low-conductivity MOFs/COFs because contact resistance is included in the measured voltage drop.
Evidence basis: review_reasoning
Caveat: Two-probe remains useful for rough initial screening when reported as such.
6 · 4.1.1. Choice of Contact Geometry · Figure 2
WBDT isolates sample-form and dopant effects within one framework chemistry, showing that oriented films can exceed pellets in some states while pellets exceed films when dopant penetration and percolation dominate.
Evidence basis: single_reference
Caveat: This is review interpretation of a single cited WBDT study.
18 · 5.3. WBDT · Table 4
Every row remains visibly secondary and links to a primary dossier only where the mapping is verified.
| Material | Property | Reported value | Context and quality | Primary evidence | Review source |
|---|---|---|---|---|---|
| SecondaryCu3BHT | electrical conductivity | 2500 S cm^-1 | Film, four-probe, room temperature Table · Exact Reported | No verified corpus mapping | 17 · 5.1. Cu3BHT · Table 2 |
| SecondaryCu3BHT | electrical conductivity | 240 S cm^-1 | Pellet, four-probe, room temperature Table · Exact Reported | No verified corpus mapping | 17 · 5.1. Cu3BHT · Table 2 |
| SecondaryCu3BHT | electrical conductivity | approximately 10000 S cm^-1 | Single crystal, four-probe, 2 K Table · Approximate | research_0113 | 17 · 5.1. Cu3BHT · Table 2 |
| SecondaryCu3BHT | electrical conductivity | approximately 1000 S cm^-1 | Single crystal, four-probe, 300 K Table · Approximate | research_0113 | 17 · 5.1. Cu3BHT · Table 2 |
| SecondaryCu3(HHTP)2 | electrical conductivity | 2.4 S cm^-1 | Film, four-probe, room temperature Table · Exact Reported | research_0417 | 17 · 5.2. CuHHTP · Table 3 |
| SecondaryCu3(HHTP)2 | electrical conductivity | 0.045 S cm^-1 | Pellet, four-probe, room temperature Table · Exact Reported | No verified corpus mapping | 17 · 5.2. CuHHTP · Table 3 |
| SecondaryCu3(HHTP)2 | electrical conductivity | 1.5 S cm^-1 | Single crystal, four-probe, 295 K Table · Exact Reported | research_0005 | 17 · 5.2. CuHHTP · Table 3 |
| SecondaryWBDT COF | electrical conductivity | 2.18 x 10^-2 S cm^-1 | Oriented film, F4TCNQ dopant/guest, room temperature Table · Exact Reported | No verified corpus mapping | 18 · 5.3. WBDT · Table 4 |
| SecondaryWBDT COF | electrical conductivity | 3.67 x 10^-2 S cm^-1 | Pellet, F4TCNQ dopant/guest, room temperature Table · Exact Reported | No verified corpus mapping | 18 · 5.3. WBDT · Table 4 |
| SecondaryWBDT COF | electrical conductivity | 4.72 x 10^-4 S cm^-1 | Pellet, I2 dopant/guest, room temperature Table · Exact Reported | No verified corpus mapping | 18 · 5.3. WBDT · Table 4 |
| SecondaryWBDT COF | electrical conductivity | 1.64 x 10^-5 S cm^-1 | Oriented film, no dopant/guest, room temperature Table · Exact Reported | No verified corpus mapping | 18 · 5.3. WBDT · Table 4 |
| SecondaryWBDT COF | electrical conductivity | 2.70 x 10^-6 S cm^-1 | Pellet, no dopant/guest, room temperature Table · Exact Reported | No verified corpus mapping | 18 · 5.3. WBDT · Table 4 |
| SecondaryWBDT COF | electrical conductivity | 6.86 x 10^-4 S cm^-1 | Oriented film, SbCl5 dopant/guest, room temperature Table · Exact Reported | No verified corpus mapping | 18 · 5.3. WBDT · Table 4 |
Open questions are presented as review-author priorities, not conclusions from the primary database.
Local and ultrafast probes can reveal idealised intragrain transport, but translation to macroscopic devices requires accounting for grain boundaries, contacts, and tortuous paths.
Proposed direction: Combine THz/TRMC with domain-size quantification and effective-medium or resistor-network modelling, then compare with DC and FET measurements on the same films.
13 · 4.4.1. Terahertz Spectroscopy
There remains a critical need to distinguish band-like and hopping processes across different structural regimes.
Proposed direction: Use complementary temperature, frequency, Hall/Seebeck, anisotropy, local-probe, and spectroscopic diagnostics rather than a single metric.
5 · 3. Electrical Conductivity in Framework Materials
The ideal workflow is experimentally demanding and usually requires collaboration across synthesis, device, local-probe, and spectroscopy groups.
Proposed direction: Use staged screening, reserving full multimodal characterisation for the most promising materials.
19 · 6. Conclusion
Designs that maximise electrical conductivity can compete with preserving the porosity that makes MOFs and COFs attractive.
Proposed direction: Develop design rules balancing pore architecture, carrier density, dielectric environment, and orbital overlap.
5 · 3. Electrical Conductivity in Framework Materials
MOF/COF films can be sensitive to humidity, temperature, residual guests, and hydrolytically sensitive linkages, complicating electronic interpretation.
Proposed direction: Report activation, atmosphere, stability checks, and residual guest assessments during film measurements.
7 · 4.1.1. Choice of Contact Geometry
Reported conductivities are difficult to compare because sample geometry, contacts, activation, atmosphere, domain size, and pellet preparation are often not standardised.
Proposed direction: Adopt method-specific reporting checklists for sample form, geometry, structure, environment, electrical settings, and complementary diagnostics.
18 · 5.3. WBDT
Mappings show which printed review references have a verified counterpart in the frozen primary corpus.
| Reference | Study | Role and context | Corpus mapping |
|---|---|---|---|
| Ref. 422022 | Title unavailable | spectroscopic_transport · transport_mechanismCited for THz photoconductivity and Drude/Drude-Smith interpretation of intragrain transport. | Unmapped |
| Ref. 512015 | Title unavailable | conduction_pathwayUsed as the review's prototypical through-bond MOF conduction example. | research_0063 |
| Ref. 522018 | Title unavailable | conduction_pathway · transport_benchmarkCited for Ni3(HITP)2 through-space stacking and pressed-pellet conductivity context. | Unmapped |
| Ref. 542017 | Title unavailable | guest_dopingCited for guest-mediated conductivity increases in TCNQ-doped MIL-53(Fe). | Unmapped |
| Ref. 622015 | Title unavailable | doping_response · spectroscopyCited for optical absorption modulation of conductive Cu3(HHTP)2 films under oxidising gases. | research_0145 |
| Ref. 682006 | Title unavailable | measurement_methodMethod reference for van der Pauw and contact-geometry measurement principles. | Unmapped |
| Ref. 822015 | Title unavailable | thin_film · device_geometryCited among thin-film approaches enabling reliable two-probe, four-probe, or Hall measurements. | research_0002 |
| Ref. 962022 | Title unavailable | thin_film · orientationCited for layer-by-layer methods that control film thickness and orientation. | research_0614 |
| Ref. 1012022 | Title unavailable | local_probe · c_afmCited for c-AFM mapping of current heterogeneity in a COF thin film. | Unmapped |
| Ref. 1192025 | Title unavailable | transport_benchmark · thin_film · case_studyCited for optimised thin-film Cu3(HHTP)2 metallic transport and Table 3 film benchmarks. | research_0417 |
| Ref. 1252019 | Title unavailable | transport_benchmark · single_crystalCited for Cu3(HHTP)2 single-crystal conductivity and material structure in the case study. | research_0005 |
| Ref. 1262018 | Title unavailable | transport_benchmark · pellet · theory_contextCited for Cu3(HHTP)2 theoretical Dirac-cone context and low pellet/film conductivity values in Table 3. | Unmapped |
| Ref. 1972021 | Title unavailable | transport_benchmark · case_study · superconductivityCited for Cu3BHT thin-film conductivity and superconducting behaviour in Figure 5 and Table 2. | Unmapped |
| Ref. 2012024 | Title unavailable | transport_benchmark · single_crystal · case_studyCited for Cu3BHT single-crystal high conductivity and superconducting transition values in Table 2. | research_0113 |
| Ref. 2042022 | Title unavailable | transport_benchmark · pellet · case_studyCited for Cu3BHT pellet conductivity in Table 2. | Unmapped |
| Ref. 2192020 | Title unavailable | transport_benchmark · doping · case_studySingle cited WBDT study underlying Table 4 pellet versus oriented-film, pristine versus doped conductivity comparison. | Unmapped |