High-mobility Materials Research Articles

Polymer-Unit Fingerprint (PUFp): An Accessible Expression of Polymer Organic Semiconductors for Machine Learning

High-performance organic semiconductors (OSCs) can be designed based on the identification of functional units and their role in the material properties. Herein, we present a polymer-unit fingerprint (PUFp) generation framework, "Python-based polymer-unit-recognition script" (PURS), to identify the subunits "polymer unit" in the polymer and generate polymer-unit fingerprint (PUFp). Using 678 collected OSC data, machine learning (ML) models can be used to determine structure-mobility relationships by using PUFp as a structural input, and the classification accuracy reaches 85.2%. A polymer-unit library consisting of 445 units is constructed, and the key polymer units affecting the mobility of OSCs are identified. By investigating the combinations of polymer units with mobility performance, a scheme for designing OSCs by combining ML approaches and PUFp information is proposed. This scheme not only passively predicts OSC mobility but also actively provides structural guidance for high-mobility OSC material design. The proposed scheme demonstrates the ability to screen materials through pre-evaluation and classification ML steps and is an alternative methodology for applying ML in high-mobility OSC discovery.

Heterojunction Transistors Printed via Instantaneous Oxidation of Liquid Metals

Semiconducting transparent metal oxides are critical high mobility materials for flexible optoelectronic devices such as displays. We introduce the continuous liquid metal printing (CLMP) technique to enable rapid roll-to-roll compatible deposition of semiconducting two-dimensional (2D) metal oxide heterostructures. We leverage CLMP to deposit 10 cm2-scale nanosheets of InOx and GaOx in seconds at a low process temperature (T < 200 °C) in air, fabricating heterojunction thin film transistors with 100× greater Ion/Ioff, 4× steeper subthreshold slope, and a 50% increase in mobility over pure InOx channels. Detailed nanoscale characterization of the heterointerface by X-ray photoelectron spectroscopy, UV-vis, and Kelvin probe elucidates the origins of enhanced electronic transport in these 2D heterojunctions. This combination of CLMP with the electrostatic control induced by the heterostructure architecture leads to high performance (μlin up to 22.6 cm2/(V s)) while reducing the process time for metal oxide transistors by greater than 100× compared with sol-gels and vacuum deposition methods.

0.2-4.0 THz broadband terahertz detector based on antenna-coupled AlGaN/GaN HEMTs arrayed in a bow-tie pattern.

To satisfy the demand for broadband and high-sensitivity terahertz detectors, we designed and verified a broadband terahertz detector built with antenna-coupled AlGaN/GaN high-electron-mobility transistors (HEMTs). Eighteen pairs of dipole antennas with different center frequency from 0.24 to 7.4 THz are arrayed into a bow-tie pattern. The corresponding eighteen transistors have common a source and a drain but different gated channels coupled by the corresponding antennas. The photocurrents generated by each gated channel are combined in the drain as the output port. With incoherent terahertz radiation from a hot blackbody in a Fourier-transform spectrometer (FTS), the detector exhibits a continuous response spectrum from 0.2 to 2.0 THz at 298 K and from 0.2 to 4.0 THz at 77 K, respectively. The results agree well with simulations taking into account the silicon lens, antenna and blackbody radiation law. The sensitivity is characterized under coherent terahertz irradiation, the average noise-equivalent power (NEP) is about 188 p W/H z at 298 K and 19 p W/H z at 77 K from 0.2 to 1.1 THz, respectively. A maximum optical responsivity of 0.56 A/W and a minimum NEP of 7.0 p W/H z at 0.74 THz are achieved at 77 K. The blackbody response spectrum is divided by the blackbody radiation intensity to obtain a performance spectrum, which is calibrated by measuring coherence performance from 0.2 to 1.1 THz to evaluate detector performance at frequencies above 1.1 THz. At 298 K, the NEP is about 1.7 n W/H z at 2.0 THz. At 77 K, the NEP is about 3 n W/H z at 4.0 THz. For further improvements in sensitivity and bandwidth, high-bandwidth coupling components, smaller series resistance, smaller gate lengths and high-mobility materials need to be considered.

Enhanced Electrical Properties of Optimized Vertical Graphene-Base Hot Electron Transistors

The arrival of high-mobility two-dimensional materials like graphene leads to the renaissance of former vertical semiconductor–metal–semiconductor (SMS) hot electron transistors. Because of the monolayer thickness of graphene, improved SMS transistors with a semimetallic graphene-base electrode are now feasible for high-frequency applications. In this study we report about a device that consists of amorphous silicon, graphene, and crystalline silicon. For the first time, this device is fabricated by a four-mask lithography process which leads to significant improvements in the device performance. A strongly increased common-emitter current gain of 2% could be achieved while the on–off ratio improved to 1.6 × 105, which is already higher than predicted theoretically. This could be mainly attributed to better interface characteristics and decreased lateral dimensions of the devices. A cutoff frequency of approximately 26 MHz could be forecasted based on the DC measurements of the device.

Impact of the Source/Drain Electrode Process on the Mobility-Threshold Trade-Off for InSnZnO Thin-Film Transistors

In this work, the source/drain (S/D) electrode process is considered to have a great impact on the mobility (μFE)–threshold (Vth) trade-off for high-mobility amorphous oxide semiconductor (AOS) thin-film transistors. High-mobility AOS materials have worse oxygen-fixation ability compared to InGaZnO. In this work, we show that this is the case for the Mo S/D electrode process on InSnZnO channels and has a great impact on the mobility-threshold trade-off. Oxygen vacancy gradients are observed in the depth profile X-ray photoelectron spectroscopy analysis on InSnZnO after Mo S/D deposition and show a bigger change in oxygen vacancies (VO) between the surface and inner layers and thicker compared to InGaZnO. This leads to an obvious negative shift in Vth or even no switching characteristic. Postprocessing such as oxygen-plasma treatment can make Vth positive but degrade the μFE. In situ replenishing oxygen via adopting ITO S/D electrodes deposited in an oxygen-containing atmosphere facilitates the achievement of excellent overall electrical characteristics, with μFE up to 87.1 cm2/Vs, Vth ∼ −0.64 V, and Ion/Ioff ∼ 2.3 × 108.

Printed n- and p-Channel Transistors using Silicon Nanoribbons Enduring Electrical, Thermal, and Mechanical Stress.

Printing technologies are changing the face of electronics with features such as resource-efficiency, low-cost, and novel form factors. While significant advances have been made in terms of organic electronics, the high-performance and stable transistors by printing, and their large-scale integration leading to fast integrated circuits remains a major challenge. This is because of the difficulties to print high-mobility semiconducting materials and the lack of high-resolution printing techniques. Herein, we present silicon based printed n- and p-channel transistors to demonstrate the possibility of developing high-performance complementary metal-oxide-semiconductor (CMOS) computing architecture. The direct roll transfer printing is used here for deterministic assembly of high-mobility single crystal silicon nanoribbons arrays on a flexible polyimide substrate. This is followed by high-resolution electrohydrodynamic printing to define source/drain/gate electrodes and to encapsulate, thus leading to printed devices. The printed transistors show effective peak mobilities of 15 cm2/(V s) (n-channel) and 5 cm2/(V s) (p-channel) at low 1 V drain bias. Furthermore, the effect of electrical, mechanical, and thermal stress on the performance and stability of the encapsulated transistors is investigated. The transistors showed stable transfer characteristics even after: (i) continuous 4000 transfer cycles, (ii) excruciating 10000 bending cycles at different bending radii (40, 25, and 15 mm), and (iii) between 15 and 60 °C temperatures.

High mobility and excellent thermoelectric performance monolayer ZnX2Z4 (X = In, Al, Ga; Z = S, Se, Te) materials.

Recently, two-dimensional (2D) layered polarized ZnIn2S4 nanosheets have been successfully synthesized in experiments. However, the polarized monolayers are unstable in air, which hinders their practical applications. Therefore, in this work, we proposed a new family of nonpolarized monolayers (β2-phase) ZnX2Z4 (X = In, Al, and Ga; Z = S, Se, and Te) by first-principles. It is confirmed that the energies of β2-phase ZnX2Z4 are lower than those of the polarized and β-phase ZnX2Z4 monolayers. Moreover, these ZnX2Z4 monolayers have not only desirable indirect band gaps but also high electron mobility (up to 103 cm2 V-1 s-1), revealing a fascinating visible light absorption range. Furthermore, β2-phase ZnX2Te4 (X = In, Al, and Ga) has ultra-low lattice thermal conductivity and high ZT value (up to 0.89), suggesting that these monolayers can be good candidates for thermoelectric materials. These new 2D ternary monolayers not only effectively broaden the family of 2D materials but also provide promising candidates for optoelectronic and thermoelectric materials.

Charge carrier mobilities of organic semiconductors: ab initio simulations with mode-specific treatment of molecular vibrations

The modeling of charge transport in organic semiconductors usually relies on the treatment of molecular vibrations by assuming a certain limiting case for all vibration modes, such as the dynamic limit in polaron theory or the quasi-static limit in transient localization theory. These opposite limits are each suitable for only a subset of modes. Here, we present a model that combines these different approaches. It is based on a separation of the vibrational spectrum and a quantum-mechanical treatment in which the slow modes generate a disorder landscape, while the fast modes generate polaron band narrowing. We apply the combined method to 20 organic crystals, including prototypical acenes, thiophenes, benzothiophenes, and their derivatives. Their mobilities span several orders of magnitude and we find a close agreement to the experimental mobilities. Further analysis reveals clear correlations to simple mobility predictors and a combination of them can be used to identify high-mobility materials.

Janus dione derivatives: Novel high-mobility hole transport materials for perovskite solar cells

Developing efficient and stable hole-transporting materials (HTMs) is very important for improving the stability and increasing the power conversion efficiency of perovskite solar cells (PSCs). Herein, novel Janus dione based HTMs with X-shaped structure were investigated using quantum chemical calculations. The results showed that introducing appropriate groups on both sides of the core led to a suitable HOMO level, good optical properties, and satisfactory stability. Importantly, due to strong inter-molecular electronic coupling, the calculated hole mobility of JT6, is as high as 7.92 cm2 V−1 s−1, which is 50 times higher than that of Spiro-OMeTAD. Simulating the adsorption properties on perovskite material CH3NH3PbI3 has also shown that these high mobility HTMs are easy to adsorb on the surface of perovskite material and can achieve good charge transfer between surface layers. The present findings highlight the potential of Janus dione core based HTMs for efficient PSCs and provide a meaningful practice for the design of HTMs with controllable HOMO levels.

Fabrication and Characterization of Micrometer Scale Graphene Structures for Large-Scale Ultra-Thin Electronics

Graphene offers many useful properties that can revolutionize modern electronic devices. Specifically, it provides high charge carrier mobility in a mechanically robust, atomically thin form factor. Many of these properties are observed in graphene which is prepared from exfoliated graphite and processed with electron beam lithography. These processes are both time intensive and cost- prohibitive for the large-scale production necessary for use in consumer electronics. This work details the processing and characterization of commercially available graphene from chemical vapor deposition (CVD) on SiO2/Si and on hBN-layered SiO2/Si wafers using conventional photolithography on the 4″ wafer standard. The findings indicate that the CVD graphene films are resilient after processing even for lengths up to 1 mm. Electrical characterization via resistance measurements and the Hall Effect at room temperature clearly indicates the influence of the substrate material on the graphene’s electrical properties. At these length scales, graphene on SiO2 resembles that of a lightly doped semiconductor in terms of its carrier density (7.8 × 1015 cm−2), yet its carrier mobility (2.6 cm2/Vs) resembles that of a metal. Graphene on hBN/SiO2 has a carrier density of 8.2 × 1012 cm−2 and carrier mobility of 2.68 × 103 cm2/Vs—comparable to existing high-mobility semiconducting materials. CVD graphene and conventional photolithography does provide a cost-effective means for producing large form-factor graphene devices for low to moderate mobility applications and eventually for large-scale monolithic graphene electronics.

Charge Transport in Organic Semiconductors: The Perspective from Nonadiabatic Molecular Dynamics.

ConspectusOrganic semiconductors (OSs) are an exciting class of materials that have enabled disruptive technologies in this century including large-area electronics, flexible displays, and inexpensive solar cells. All of these technologies rely on the motion of electrical charges within the material and the diffusivity of these charges critically determines their performance. In this respect, it is remarkable that the nature of the charge transport in these materials has puzzled the community for so many years, even for apparently simple systems such as molecular single crystals: some experiments would better fit an interpretation in terms of a localized particle picture, akin to molecular or biological electron transfer, while others are in better agreement with a wave-like interpretation, more akin to band transport in metals.Exciting recent progress in the theory and simulation of charge carrier transport in OSs has now led to a unified understanding of these disparate findings, and this Account will review one of these tools developed in our laboratory in some detail: direct charge carrier propagation by quantum-classical nonadiabatic molecular dynamics. One finds that even in defect-free crystals the charge carrier can either localize on a single molecule or substantially delocalize over a large number of molecules depending on the relative strength of electronic couplings between the molecules, reorganization, or charge trapping energy of the molecule and thermal fluctuations of electronic couplings and site energies, also known as electron–phonon couplings.Our simulations predict that in molecular OSs exhibiting some of the highest measured charge mobilities to date, the charge carrier forms “flickering” polarons, objects that are delocalized over 10–20 molecules on average and that constantly change their shape and extension under the influence of thermal disorder. The flickering polarons propagate through the OS by short (≈10 fs long) bursts of the wave function that lead to an expansion of the polaron to about twice its size, resulting in spatial displacement, carrier diffusion, charge mobility, and electrical conductivity. Arguably best termed “transient delocalization”, this mechanistic scenario is very similar to the one assumed in transient localization theory and supports its assertions. We also review recent applications of our methodology to charge transport in disordered and nanocrystalline samples, which allows us to understand the influence of defects and grain boundaries on the charge propagation.Unfortunately, the energetically favorable packing structures of typical OSs, whether molecular or polymeric, places fundamental constraints on charge mobilities/electronic conductivity compared to inorganic semiconductors, which limits their range of applications. In this Account, we review the design rules that could pave the way for new very high-mobility OS materials and we argue that 2D covalent organic frameworks are one of the most promising candidates to satisfy them.We conclude that our nonadiabatic dynamics method is a powerful approach for predicting charge carrier transport in crystalline and disordered materials. We close with a brief outlook on extensions of the method to exciton transport, dissociation, and recombination. This will bring us a step closer to an understanding of the birth, survival, and annihiliation of charges at interfaces of optoelectronic devices.

Highly sensitive photomultiplication type polymer photodetectors by manipulating interfacial trapped electron density

Photomultiplication type polymer photodetectors (PM-PPDs) are successfully achieved via interfacial trap-assisted hole tunneling injection from external circuit. The external quantum efficiency (EQE) of PM-PPDs is mainly determined by the number of injected holes from external circuit and flowing across the devices. Although the trapped electron density near Al electrode can be increased for efficient hole tunneling injection by decreasing the thickness of active layers, which also makes the PM-PPDs vulnerable to breakdown. A smart strategy is firstly proposed to obtain large EQE values by decreasing the thickness of active layers and keep excellent withstanding large bias characteristic of PM-PPDs by using wide bandgap polymer poly-TPD as buffer layer. The optimal double layered ternary PM-PPDs were obtained with 40 nm poly-TPD as buffer layer and 90 nm P3HT:PBDB-T:PC61BM (80:20:2, wt/wt/wt) as active layers, exhibiting a rather large EQE value of 21400% and specific detectivity of 1.0 × 1013 Jones at 430 nm under −8 V bias. This work indicates that inserting wide bandgap and high hole mobility material as buffer layer should be an efficient strategy to prepare highly sensitive PM-PPDs, benefiting from the increased hole tunneling injection from external circuit and efficient hole flowing across the devices.

Abnormally weak intervalley electron scattering in MoS2 monolayer: insights from the matching between electron and phonon bands.

It is known that carrier mobility in layered semiconductors generally increases from two-dimensions (2D) to three-dimensions due to fewer scattering channels resulting from decreased densities of electron and phonon states. In this work, we find an abnormal decrease of electron mobility from monolayer to bulk MoS2. By carefully analyzing the scattering mechanisms, we can attribute such abnormality to the stronger intravalley scattering in the monolayer but weaker intervalley scattering caused by few intervalley scattering channels and weaker corresponding electron-phonon couplings compared to the bulk case. We show that it is the matching between the electronic band structure and phonon spectrum rather than their densities of electronic and phonon states that determines scattering channels. We propose, for the first time, the phonon-energy-resolved matching function to identify the intra- and inter-valley scattering channels. Furthermore, we show that multiple valleys do not necessarily lead to strong intervalley scattering if: (1) the scattering channels, which can be explicitly captured by the distribution of the matching function, are few due to the small matching between the corresponding electron and phonon bands; and/or (2) the multiple valleys are far apart in the reciprocal space and composed of out-of-plane orbitals so that the corresponding electron-phonon coupling strengths are weak. Consequently, the searching scope of high-mobility 2D materials can be reasonably enlarged using the matching function as useful guidance with the help of band edge orbital analysis.

Boosting the performance of solution-processed quantum dots light-emitting diodes by a hybrid emissive layer via doping small molecule hole transport materials into quantum dots

Solution-processed colloidal quantum dot light-emitting diodes (QLED) have attracted many attentions with significant progress in recent years. However, QLED devices still face some challenges. The energy barrier between Cd-base quantum dots (QDs) and commonly used hole transport materials is larger than that between QDs and electron transport materials, which leads to the imbalance of carriers in the light emitting layer (EML) and the low performance of QLED devices. Herein, we report a simple strategy to improve the device performance by doping small molecule transport material 4,4′-cyclohexylidenebis[N,N-bis(p-tolyl)aniline] (TAPC) into red CdSe/ZnS QDs. The optimized red QLED devices with TAPC-doped emissive layer at a ratio of 3.2 wt% achieve 20.0 cd/A of maximum current efficiency, 16.6 lm/W of power efficiency and 15.7% of external quantum efficiency, which is 30%, 58% and 33% higher than the control device. The improved performance of devices can be ascribed to the increase of hole current density, decrease of leakage electrons and more balanced quantity of carriers in EML. This work put forward a viewpoint to improve the performance of QLED devices via doping high hole mobility materials into emission layer. • Small molecule hole transport material TAPC is doped into red CdSe/ZnS QDs to enhance the device performance. • The EML solution consists of QD octane solution and TAPC o-xylene solution. • The introduction of TAPC leads to the reduction of leakage electrons and the improvement of hole density.

Spin–orbit coupling effect on electronic, linear and nonlinear optical properties of Bi2S3 and the ternary bismuth sulfide Bi2S2.75Se0.25: Ab-initio calculations

Although the relevant properties of the bismuthinite Bi2S3, it was recently approved that the substitution of Se atoms in the Bi2S3 lattice can significantly enhance its electro-optical properties. In the present work, a detailed study on the structural, electronic and optical properties of Bi2S2.75Se0.25 has been carried out based on first principle calculations. The simultaneous effect of Se-doping and spin–orbit coupling (SOC) on bismuth sulfide Bi2S3 was investigated. Our calculations show that Bi2S2.75Se0.25 exhibits a narrow direct band gap of 1.062 eV after inclusion of the (SOC). The calculation of the carrier effective masses indicates that Bi2S2.75Se0.25 may possess a high electron mobility material which is in accordance with experimental studies. The linear absorption optical spectra for both Bi2S3 and Bi2S2.75Se0.25 show that doping bismuthinite with (Se) increases the optical absorption coefficient in the visible range and takes a value up to 10105 cm−1. In addition, the dielectric function, optical conductivity and the energy loss function of Bi2S3 and Bi2S2.75Se0.25 were also derived. The addition of the (Se) content induces a red shift in agreement with experimental studies. A noticeable effect of the (SOC) on the linear optical parameters was observed. The stability of the excitons was also studied by the estimation of the binding energy value. The dispersion energy parameters of Bi2S3 and Bi2S2.75Se0.25 were estimated using a single oscillator model. Some nonlinearities have been computed with and without inclusion of (SOC) showing that Bi2S2.75Se0.25 with large nonlinear optical parameters is promising candidate in photonic switching applications.

A wide-bandgap, high-mobility electron-transporting material containing a 9,9′-spirobithioxanthene skeleton

The efficiency and stability of organic light-emitting diodes (OLEDs) are highly dependent on the balance of carriers in the emitting layer. The lack of wide-bandgap and high-mobility electron-transporting material (ETM) has restricted the performance and processing of blue fluorescent OLEDs (FOLEDs) and green phosphorescent OLEDs (PHOLEDs) in the display industry. Herein, on the basis of a p-π conjugated 9,9′-spirobithioxanthene skeleton, a novel ETM with S and C atoms bridging phenylpyridine functional units (T3PySS) was designed and synthesized. Such a rigid and symmetrically orthogonal molecule exhibited a high triplet energy level of 2.7 eV and electron mobility comparable to the most conductive ETMs. The investigation on the bridge atom and the number of functional groups in this type of ETMs revealed that balanced inter- and intramolecular electron coupling was critical to achieving high-mobility, wide-bandgap ETM. The deep-blue FOLEDs (CIEy = 0.07) with a T3PySS electron-transporting layer reached a current density of 20 mA/cm2 and a luminescence of approximately 1000 cd/m2 at a voltage as low as 3.2 V while showing improved efficiency and stability compared to the control devices based on classical ETMs. Owing to improved charge balance, the stability of green PHOLEDs employing T3PySS was also superior to that of devices based on traditional high triplet energy ETMs.

Precision measurement of electron-electron scattering in GaAs/AlGaAs using transverse magnetic focusing

Electron-electron (e-e) interactions assume a cardinal role in solid-state physics. Quantifying the e-e scattering length is hence critical. In this paper we show that the mesoscopic phenomenon of transverse magnetic focusing (TMF) in two-dimensional electron systems forms a precise and sensitive technique to measure this length scale. Conversely we quantitatively demonstrate that e-e scattering is the predominant effect limiting TMF amplitudes in high-mobility materials. Using high-resolution kinetic simulations, we show that the TMF amplitude at a maximum decays exponentially as a function of the e-e scattering length, which leads to a ready approach to extract this length from the measured TMF amplitudes. The approach is applied to measure the temperature-dependent e-e scattering length in high-mobility GaAs/AlGaAs heterostructures. The simulations further reveal current vortices that accompany the cyclotron orbits - a collective phenomenon counterintuitive to the ballistic transport underlying a TMF setting.

Suppression of Hot‐Carrier Effects Facilitated by the Multimodal Thin‐Film Transistor Architecture

AbstractHot‐carrier effects are a persistent challenge for Ohmic contact, high carrier mobility thin‐film transistors. As semiconductor properties are systematically improved, such phenomena (e.g., the kink effect) are becoming apparent even in materials such as InGaZnO. Few of the past solutions are practical in these low‐complexity semiconductor systems. Here, it is shown that contact‐controlled devices offer robust performance under extreme biasing conditions due to their distinctive charge injection processes. The recently‐developed multimodal transistor (MMT) provides further control still, by separate regulation of current flow and magnitude. Internal electric field distributions in the source and drain regions are studied via technology computer‐aided design simulations, and support the formulation of operational guidelines for the MMT's channel control gate for optimal characteristics in saturation. As MMT principles are universal, these findings should inform device design and operation in all high carrier mobility material systems.

2D materials for conducting holes from grain boundaries in perovskite solar cells

Grain boundaries in organic–inorganic halide perovskite solar cells (PSCs) have been found to be detrimental to the photovoltaic performance of devices. Here, we develop a unique approach to overcome this problem by modifying the edges of perovskite grain boundaries with flakes of high-mobility two-dimensional (2D) materials via a convenient solution process. A synergistic effect between the 2D flakes and perovskite grain boundaries is observed for the first time, which can significantly enhance the performance of PSCs. We find that the 2D flakes can conduct holes from the grain boundaries to the hole transport layers in PSCs, thereby making hole channels in the grain boundaries of the devices. Hence, 2D flakes with high carrier mobilities and short distances to grain boundaries can induce a more pronounced performance enhancement of the devices. This work presents a cost-effective strategy for improving the performance of PSCs by using high-mobility 2D materials.

Doped Highly Crystalline Organic Films: Toward High-Performance Organic Electronics.

Today's organic electronic devices, such as the highly successful OLED displays, are based on disordered films, with carrier mobilities orders of magnitude below those of inorganic semiconductors like silicon or GaAs. For organic devices such as diodes and transistors, higher charge carrier mobilities are paramount to achieve high performance. Organic single crystals have been shown to offer these required high mobilities. However, manufacturing and processing of these crystals are complex, rendering their use outside of laboratory‐scale applications negligible. Furthermore, doping cannot be easily integrated into these systems, which is particularly problematic for devices mandating high mobility materials. Here, it is demonstrated for the model system rubrene that highly ordered, doped thin films can be prepared, allowing high‐performance organic devices on almost any substrate. Specifically, triclinic rubrene crystals are created by abrupt heating of amorphous layers and can be electrically doped during the epitaxial growth process to achieve hole or electron conduction. Analysis of the space charge limited current in these films reveals record vertical mobilities of 10.3(49) cm2 V−1 s−1. To demonstrate the performance of this materials system, monolithic pin‐diodes aimed for rectification are built. The f3db of these diodes is over 1 GHz and thus higher than any other organic semiconductor‐based device shown so far. It is believed that this work will pave the way for future high‐performance organic devices based on highly crystalline thin films.