Two-dimensional conjugated metal-organic frameworks (2D c-MOFs) have attracted increasing interests for (opto)-electronics and spintronics. They generally consist of van der Waals stacked layers and exhibit layer-depended electronic properties. While considerable efforts have been made to regulate the charge transport within a layer, precise control of electronic coupling between layers has not yet been achieved. Herein, we report a strategy to precisely tune interlayer charge transport in 2D c-MOFs via side-chain induced control of the layer spacing. We design hexaiminotriindole ligands allowing programmed functionalization with tailored alkyl chains (HATI_CX, X = 1,3,4; X refers to the carbon numbers of the alkyl chains) for the synthesis of semiconducting Ni3(HATI_CX)2. The layer spacing of these MOFs can be precisely varied from 3.40 to 3.70 Å, leading to widened band gap, suppressed carrier mobilities, and significant improvement of the Seebeck coefficient. With this demonstration, we further achieve a record-high thermoelectric power factor of 68 ± 3 nW m−1 K−2 in Ni3(HATI_C3)2, superior to the reported holes-dominated MOFs.

Two‐dimensional conjugated metal–organic frameworks (2D c‐MOFs) are emerging as a unique class of electronic materials. However, 2D c‐MOFs with band gaps in the Vis‐NIR and high charge carrier mobility are rare. Most of the reported conducting 2D c‐MOFs are metallic (i.e. gapless), which largely limits their use in logic devices. Herein, we design a phenanthrotriphenylene‐based, D2h‐symmetric π‐extended ligand (OHPTP), and synthesize the first rhombic 2D c‐MOF single crystals (Cu2(OHPTP)). The continuous rotation electron diffraction (cRED) analysis unveils the orthorhombic crystal structure at the atomic level with a unique slipped AA stacking. The Cu2(OHPTP) is a p‐type semiconductor with an indirect band gap of ≈0.50 eV and exhibits high electrical conductivity of 0.10 S cm−1 and high charge carrier mobility of ≈10.0 cm2 V−1 s−1. Theoretical calculations underline the predominant role of the out‐of‐plane charge transport in this semiquinone‐based 2D c‐MOF.

Zweidimensionale konjugierte metallorganische Gerüstverbindungen (2D c-MOFs) gehören zu einer einzigartigen Gruppe elektronischer Materialien. 2D c-MOFs mit Bandlücken im sichtbaren oder nahen IR-Bereich und hohen Ladungsträger-mobilitäten sind jedoch rar. Die meisten literaturbekannten halbleitenden 2D c-MOFs sind metallisch, was ihre Verwendung in logischen Bauelementen stark einschränkt. Im Folgenden konzipieren wir einen Phenanthrotriphenylen basierten, D 2h -symmetrischen, π-konjugierten Liganden (OHPTP) und synthetisieren die ersten rhombischen 2D c-MOF Einkristalle (Cu 2 (OHPTP)). Kontinuierliche Rotations-Elektronendiffraktometrie (cRED) belegt die orthorhombische Kristallstruktur mit versschobene AA-Schichtung auf atomarer Ebene. Cu 2 (OHPTP) ist ein p-Typ Halbleiter mit einer indirekten Bandlücke von � 0.50 eV, einer hohen elektrischen Leitfähigkeit von 0.10 S cm À 1 und einer hohen Ladungsträgermobilität von � 10.0 cm 2 V À 1 s À 1 . Theoretische Berechnungen unterstreichen die dominierende Rolle des Ladungstransports zwischen den Schichten in diesem Semichinon verknüpften 2D c-MOF.

Here, we analyze in a non-contact fashion charge carrier mobility as a function of injection level and temperature in silicon by time resolved THz spectroscopy (TRTS) and parametrize our data by the classical semi-empirical models of Klaassen and Dorkel & Leturcq. Our experimental results are in very good agreement with the pioneering works of Krausse and Dännhauser analyzing this phenomena by employing contact-based methods. This agreement, that validates our methodology, can only be achieved by considering charge carrier diffusion effects following above bandgap near-surface pump photo-excitation of the sample. From our results, obtained over a large range of injection levels, we conclude that the model of Klaassen is the best on describing the collected data at room temperature. Furthermore, we analyze by TRTS the dependence of charge carrier mobility with temperature for a fixed injection level. Once more, the parametrization made by the classical model of Klaassen describe our data appropriately even without the necessity of applying any fitting parameters (just with the charge carrier density as an input). In this respect, our work supports the validity of the model and parametrization proposed by Klaassen, and also illustrate how TRTS can be reliably employed for the quantitative determination of mobility in semiconductors as a function of key parameters as injection level and temperature.

By means of Terahertz Spectroscopy we demonstrate a boost in charge carrier mobility in upgraded-metallurgical grade silicon wafers treated by phosphorous diffusion gettering. Mobilities parallel those of high quality poly-Si.