Ambipolar Transport Properties Research Articles

Electrically reconfigurable MoO3/InSe van der Waals heterojunctions

Abstract Van der Waals (vdW) heterojunctions formed by stacking different layers of two-dimensional atomic crystals with atomically sharp interface and versatile band alignment have been considered as promising candidates for construction of nanoelectronic and nanophotonic devices. Here, we demonstrate the electrically reconfigurable behavior in MoO3/InSe vdW heterojunction with a type-III broken-gap band alignment. The electrical reconfigurability is enabled by the ambipolar transport property of InSe, which is achieved through the use of Pt as contact electrodes. By electrostatically doping the indium selenide (InSe), the reconfigurable MoO3/InSe heterojunctions can be converted between p-n and n+-n junctions. As a current rectifier, the MoO3/InSe heterojunction shows rectification ratios of ~ 107 and ~104 for forward and backward bias conditions, respectively. As a photodetector, the MoO3/InSe heterojunction shows stable photo-switching behavior with a ~105 on/off ratio and an ultralow dark current (≈10 fA).The response time is measured to be 500 μs and 300 μs for rise and fall processes, respectively. These results highlight the role of MoO3 with high electron affinity in construction of vdW heterostructure with type-III band alignment and provide a new platform for high performance optoelectronic devices.

Blue emitting exciplex for yellow and white organic light-emitting diodes

White organic light-emitting diodes (WOLEDs) have several desirable features, but their commercialization is hindered by the poor stability of blue light emitters and high production costs due to complicated device structures. Herein, we investigate a standard blue emitting hole transporting material (HTM) N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPB) and its exciplex emission upon combining with a suitable electron transporting material (ETM), 3-(biphenyl-4-yl)-5-(4-tert-butylphenyl)-4-phenyl-4H-1,2,4-triazole (TAZ). Blue and yellow OLEDs with simple device structures are developed by using a blend layer, NPB:TAZ, as a blue emitter as well as a host for yellow phosphorescent dopant iridium (III) bis(4-phenylthieno[3,2-c]pyridinato-N,C2')acetylacetonate (PO-01). Strategic device design then exploits the ambipolar charge transport properties of tetracene as a spacer layer to connect these blue and yellow emitting units. The tetracene-linked device demonstrates more promising results compared to those using a conventional charge generation layer (CGL). Judicious choice of the spacer prevents exciton diffusion from the blue emitter unit, yet facilitates charge carrier transport to the yellow emitter unit to enable additional exciplex formation. This complementary behavior of the spacer improves the blue emission properties concomitantly yielding reasonable yellow emission. The overall white light emission properties are enhanced, achieving CIE coordinates (0.36, 0.39) and color temperature (4643 K) similar to daylight. Employing intermolecular exciplex emission in OLEDs simplifies the device architecture via its dual functionality as a host and as an emitter.Graphical abstract

Conjugated Polymers from Direct Arylation Polycondensation of 3,4-Difluorothiophene-Substituted Aryls: Synthesis and Properties.

3,4-Difluorothiophene-substituted aryls, i.e., 1,4-bis(3,4-difluorothiophen-2-yl)-benzene (Ph-2FTh), 1,4-bis(3,4-difluorothiophen-2-yl)-2,5-difluorobenzene (2FPh-2FTh), and 4,7-bis(3,4-difluorothiophen-2-yl)-2,1,3-benzothiadiazole (BTz-2FTh), are synthesized as C─H monomers for the synthesis of conjugated polymers (CPs) via direct arylation polycondensation (DArP) with diketopyrrolopyrrole (DPP) and isoindigo (IID) derivatives as C─Br monomers. The Gibbs free energies of activation for direct arylation (ΔG298K , kcal mol-1 ) for α─C─H bonds of thiophene moieties as calculated by density functional theory (DFT) are 14.3, 16.5, and 16.4kcal mol-1 for Ph-2FTh, 2FPh-2FTh and BTz-2FTh, respectively, meaning that inserting an electron-deficient unit in 3,3',4,4'-tetrafluoro-2,2'-bithiophene (4FBT, ΔG298K : 14.6kcal mol-1 ) may cause a reactivity decrease of the C─H monomers. Photophysical and semiconducting properties of the resulting six CPs (i.e., DPP-Ph, DPP-2FPh, DPP-BTz, 2FIID-Ph, 2FIID-2FPh, and 2FIID-BTz) are characterized in detail. DPP-based CPs show ambipolar transport properties while IID-based ones exhibited n-type behavior owing to the deeper frontier molecular orbital energy levels of IID-based CPs. With source/drain electrodes modified with polyethylenimine ethoxylated, n-channel organic thin-film transistors with maximum electron mobility of 0.40, 0.54, 0.29, 0.05, 0.16, and 0.01 cm2 V-1 s-1 for DPP-Ph, DPP-2FPh, DPP-BTz, 2FIID-Ph, 2FIID-2FPh, and 2FIID-BTz, respectively, are fabricated. DPP-2FPh exhibits the best device performance due to the good film morphology and the highest intermolecular packing order.

Three-dimensional inter-layer optical signal transmission realized by a monolithically integrated semiconductor-based carrier transport structure.

In this study, we proposed and demonstrated a brand new type of monolithic photonic devices which realizes the three-dimensional (3D) all-optical switching for inter-layer signal transmission. This device is composed of a vertical Si microrod which serves as optical absorption material within a SiN waveguide in one layer and as an index modulation structure within a SiN microdisk resonator lying in the other layer. The ambipolar photo-carrier transport property in the Si microrod was studied by measuring the resonant wavelength shifts under continuous-wave laser pumping. The ambipolar diffusion length can be extracted to be 0.88 µm. Based on the ambipolar photo-carrier transport in a Si microrod through different layers, we presented a fully-integrated all-optical switching operation using this Si microrod and a SiN microdisk with a pump-probe technique through the on-chip SiN waveguides. The switching time windows for the on-resonance operation mode and the off-resonance operation mode can be extracted to be 439 ps and 87 ps, respectively. This device shows potential applications for the future all-optical computing and communication with more practical and flexible configurations in monolithic 3D photonic integrated circuits (3D-PICs).

Bismuth-Based Halide Perovskites for Photocatalytic H2 Evolution Application.

Metal halide perovskites (MHPs), in particular lead-based perovskites, have earned recognized fame in several fields for their outstanding optoelectronic properties, including direct generation of free charge carriers, optimal ambipolar charge carrier transport properties, high absorption coefficient, point-defect tolerance, and compositional versatility. Nowadays, this class of materials represents a real and promising alternative to silicon for photovoltaic technologies. This worthy success led to a growing interest in the exploration of MHPs in other hot research fields, such as solar-driven photocatalytic water splitting towards hydrogen production. Nevertheless, many of these perovskites show air and moisture instability problems that considerably hinder their practical application for photocatalytic water splitting. Moreover, if chemical instability is a problem that can be in part mitigated by the optimization of the chemical composition and crystal structure, the presence of lead represents a real problem for the practical application of MHPs in commercial devices due to environmental and healthcare issues. To successfully overcome these problems, lead-free metal halide perovskites (LFMHPs) have gained increasing interest thanks to their optoelectronic properties, comparable to lead-based materials, and their more eco-friendly nature. Among all the lead-free perovskite alternatives, this mini-review considers bismuth-based perovskites and perovskite derivatives with a specific focus on solar-driven photocatalysis application for H2 evolution. Special attention is dedicated to the structure and composition of the different materials and to the advantage of heterojunction engineering and the relative impact on the photocatalytic process.

Molecular Engineering of Printed Semiconducting Blends to Develop Organic Integrated Circuits: Crystallization, Charge Transport, and Device Application Analyses.

Solution-based printing has contributed to the facile deposition of various types of materials, including the building blocks of printed electronics. In particular, solution-processable organic semiconductors (OSCs) are regarded as one of the most fascinating candidates for the fabrication of printed electronics. Herein, we report electrohydrodynamic (EHD) jet-printed p- and n-type OSCs, namely 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-PEN) and 6,13-bis((triisopropylsilyl)ethynyl)-5,7,12,14-tetraazapentacene (TIPS-TAP), and their use as single-OSC layers and as OSC mixed p-n layers to fabricate solution-processed p-, n-, and ambipolar-type organic field-effect transistors (OFETs). Use of the dragging mode of EHD jet printing, a process driven under a low electrostatic field with a short nozzle-to-substrate distance, was found to provide favorable conditions for growth of TIPS-PEN and TIPS-TAP crystals. In this way, the similar molecular structures of TIPS-PEN and TIPS-TAP yielded a homogeneous solid solution and showed ambipolar transport properties in OFETs. Therefore, the combination of single- and mixed-OSC layers enabled the preparation of various charge-transported devices from unit to integrated devices (NOT, NAND, NOR, and multivalued logic). Therefore, this fabrication technology can be useful for assisting in the production of OSC layers for practical applications in the near future.

Interplay between Charge Injection, Electron Transport, and Quantum Efficiency in Ambipolar Trilayer Organic Light‐Emitting Transistors

AbstractThe fascinating characteristic of organic light‐emitting transistors (OLETs) of being electrical switches with an intrinsic light‐emitting capability makes them attractive candidates for a wide variety of applications, ranging from sensors to displays. To date, the OLET ambipolar trilayer heterostructure is the most developed architecture for maximizing device performance. However, a major challenge of trilayer OLETs remains the inverse correlation between external quantum efficiency and brightness under ambipolar conditions. The complex interconnection between electroluminescent and ambipolar charge transport properties, in conjunction with the limited availability of electron transport semiconducting materials, has indeed hampered the disruptive evolution of the OLET technology. Here, an in‐depth study of the interplay of the key fundamental features that determine the device performance is reported by exploring electron transport semiconductors with different properties in ambipolar trilayer OLETs. Through the selection of compounds with tailored chemical structures, the relation between intrinsic optoelectronic characteristics of the electron transport semiconductor, energy level alignment within the structure, and morphological features is unraveled. Furthermore, the introduction of a suitable electron injector at the emissive/semiconducting layers interface sheds light into the bidimensional nature of OLETs that is a distinguishing factor of this class of devices with respect to prototypical organic light‐emitting diodes.

Growth direction dependent separate-channel charge transport in the organic weak charge-transfer co-crystal of anthracene-DTTCNQ.

Co-crystallization is an efficient way of molecular crystal engineering to tune the electronic properties of organic semiconductors. In this work, we synthesized anthracene-4,8-bis(dicyanomethylene)4,8-dihydrobenzo[1,2-b:4,5-b']-dithiophene (DTTCNQ) single crystals as a template to study the crystal growth direction dependent charge transport properties and attempted to elucidate the mechanism by proposing a separate-channel charge transport model. Single-crystal anthracene-DTTCNQ field-effect transistors showed that ambipolar transport properties could be observed in all crystal growth directions. Furthermore, upon changing the measured crystal directions, the electronic properties experienced a weak change from n-type dominated ambipolar, balanced ambipolar, to p-type dominated ambipolar properties. The theoretical calculations at density functional theory (DFT) and higher theory levels suggested that the anthracene-DTTCNQ co-crystal motif was a weak charge-transfer complex, in line with the experiment. Furthermore, the detailed theoretical analysis also indicated that electron or hole transport properties originated from separated channels formed by DTTCNQ or anthracene molecules. We thus proposed a novel separate-channel transport mechanism to support additional theoretical analysis and calculations. The joint experimental and theoretical efforts in this work suggest that the engineering of co-crystallization of weak charge-transfer complexes can be a practical approach for achieving tuneable ambipolar charge transport properties by the rational choice of co-crystal formers.

Deciphering the Role of Defects in the Ambipolar Electrical Transport in Nanocrystalline Sb2Se3 Thin Films

AbstractThe role of two defects in the ambipolar character of nanocrystalline selenium poor Sb2Se3 is studied. At low temperature, the electrical transport in Sb2Se3 thin films with nm‐sized crystallites and grains is dominated by the ionization of a shallow acceptor, while at high temperature a deep donor is the leading one. The ionization energy of the deep donor agrees with theoretical reports for selenium vacancies. However, the value of the ionization energy of the shallow acceptor is in contradiction with theoretical reports pointing out to an unreported shallow defect. These findings have been confirmed by two independent experimental techniques, Electron Paramagnetic Resonance, and electrical transport as a function of temperature. The mobility of the free carriers has been found not to be limited by grain potential barriers (GPB), in contrast with polycrystalline thin films. Both findings, new shallow acceptor and zero height GPB, constitute advantages for the design of nanostructured Sb2Se3‐based solar cells and other optoelectronic devices. These results not only provide useful information for the growth of nanocrystalline Sb2Se3 thin films with ambipolar transport properties, but also about the complexity of defect physics in low‐symmetry and Q1D semiconductors.

Unveiling the ambipolar carrier transport property of SnO2−X for multiple-functional interlayers in perovskite solar cells

Tin oxides are the most promising electron transport layers in perovskite solar cells. An ambipolar carrier transport property has been recently demonstrated which enables a simple interconnection structure for all-perovskite tandem solar cells. However, the underlying mechanism for its ambipolar behavior is unclear, which cannot be explained by the intrinsic defects in SnO2−x. Here, by using density functional theory calculations, we unveil the origin of the ambipolar carrier transport of non-stoichiometry SnO2−x with a structure of SnO embedded in the SnO2 matrix. The hybridization of O 2p and Sn 5s orbitals of SnO introduces mid-gap states in the bandgap of SnO2, enabling hole transport property for SnO2−x when x is > 0.2. Increasing the percentage of SnO in SnO2−x significantly enhances the hole transport capability of SnO2−x due to the enlarged Sn–O–Sn angles that increase orbital overlapping between O and Sn atoms, thus providing strategies for the further tuning of the carrier transport properties of SnO2−x by compositional and structural designs.

Ambipolar carrier transport properties of triphenylamine/dibenzofulvene derivative and its application for efficient n-i-p perovskite solar cells

Herein, the carrier transport properties of 9-(4-(diphenylamino)benzylidene)-N′,N′,N′,N′-tetraphenyl-9H-fluorene-2,7-diamine (YC-1) was firstly investigated with time-of-flight method. YC-1 exhibited ambipolar conductive behaviour, with hole and electron mobilities up to 10−4 cm2(Vs)−1. We introduced YC-1 as a hole transporting layer (HTL) in a planar n-i-p perovskite solar cell. A device fabricated using YC-1 exhibited enhanced performance compared to the device fabricated using P3HT, demonstrating 14.91% power conversion efficiency (PCE) and low hysteresis with a hysteresis effect index (HEI) of 0.007. A comprehensive analysis of the J-V characteristics in hole-only devices revealed the improvement of the YC-1 based devices were mainly contributed to the higher conductivity and lower trap density, which were beneficial to the device performance. This work suggests the thermally evaporable triphenylamine/dibenzofulvene can be a good candidate for HTL of conventional perovskite solar cells.

Novel DPP derivatives functionalized with auxiliary electron-acceptor groups and characterized by narrow bandgap and ambipolar charge transport properties

Four novel diketopyrrolopyrrole (DPP) derivatives have been synthesized and characterized: the dyes are based on a DPP electron acceptor core symmetrically functionalized with donor bi-furyl moieties and end capped with four different auxiliary electron-acceptor groups. Because of the alternation along the molecular backbone of electron acceptor and donor groups, all the dyes are characterized by optical absorption maxima approaching or exceeding 700 nm. In the solid state, this optical behavior determines for all the dyes a very low optical bandgap ranging from 1.57 eV to 1.29 eV, while electrochemical characterization shows a clear dependence of the LUMO energies on the strength of the auxiliary electron-acceptor groups. All the dyes are characterized by stable LUMO energies suitable for their application as n-type semiconductors. Organic field-effect transistors based on the reported compounds display actually n-type behavior and, in three cases, a very interesting and balanced ambipolar charge transport behavior was moreover observed.

Design and Synthesis of Annulated Benzothiadiazoles via Dithiolate Formation for Ambipolar Organic Semiconductors.

Substituted 2,1,3-benzothiadiazole (BTD) is a widely used electron acceptor unit for functional organic semiconductors. Difluorination or annulation on the 5,6-position of the benzene ring is among the most adapted chemical modifications to tune the electronic properties, though each sees its own limitations in regulating the frontier orbital levels. Herein, a hitherto unreported 5,6-annulated BTD acceptor, denoted as ssBTD, is designed and synthesized by incorporating an electron-withdrawing 2-(1,3-dithiol-2-ylidene)malononitrile moiety via aromatic nucleophilic substitution of the 5,6-difluoroBTD (ffBTD) precursor. Unlike the other reported BTD annulation strategies, this modification leads to the simultaneous decrease in both frontier orbital energies, a welcoming feature for photovoltaic applications. Incorporation of ssBTD into conjugated polymers results in materials boasting broad light absorption, dramatic solvatochromic and thermochromic responses (>100 nm shift and a band gap difference of ∼0.28 eV), and improved crystallinity in the solid state. Such physical properties are in accordance with the combined electron-withdrawing effect and significantly increased polarity associated with the ssBTD unit, as revealed by detailed theoretical studies. Furthermore, the thiolated ssBTD imbues the polymer with ambipolar charge transport property, in contrast to the ffBTD-based polymer, which transports holes only. While the low mobilities (10-4 to 10-5 cm2 V-1 s-1) could be further optimized, detailed studies validate that the thioannulated BTD is a versatile electron-accepting unit for the design of functional stimuli-responsive optoelectronic materials.

A-D-A Type Semiconducting Small Molecules with Bis(alkylsulfanyl)methylene Substituents and Control of Charge Polarity for Organic Field-Effect Transistors.

In this study, we synthesize four different kinds of bis(alkylsulfanyl)methylene-substituted 4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene (IDT)-based acceptor-donor-acceptor (A-D-A) type small molecules (IDSIC, IDSIC-4F, IDSIC-4Cl, and IDSTIC) by incorporating electron-withdrawing halogen atoms or electron-releasing thiophene spacers. Herein, enhanced structural planarity and crystalline intermolecular packing are induced by the sp2-hybridized C═C double bond side chains and sulfur-sulfur chalcogen interactions. The fine control of intramolecular charge transfer modulates the electrochemical characteristics and the resulting carrier polarity in organic field-effect transistors (OFETs). Well-balanced ambipolar, n-dominant, and p-dominant charge transport properties are successfully demonstrated in OFETs by modulating the electron-donating or withdrawing strength based on the A-D-A structural motif, resulting in hole/electron mobilities of 0.599/0.553, 0.003/0.019, 0.092/0.897, and 0.683/0.103 cm2/V·s for IDSIC, IDSIC-4F, IDSIC-4Cl, and IDSTIC respectively, after thermal annealing at 200 °C. Thermal annealing of the as-cast films improves the intermolecular packing in an edge-on fashion, which is investigated in detail by grazing incidence X-ray scattering. Finally, complementary logic circuits, i.e., NOT, NAND, and NOR, are fabricated by assembling p-dominant IDSTIC and n-dominant IDSIC-4Cl OFETs. Therefore, a simple and efficient molecular design strategy for fine tuning the charge polarity and charge transport properties of OFET devices is presented.

Quinoidal bisthienoisatin based semiconductors: Synthesis, characterization, and carrier transport property

AbstractNovel quinoidal bisthienoisatin (QBTI) derivatives end‐capped with phenyl and thienyl groups were designed and synthesized. Single‐crystal X‐ray structure analysis of phenyl group flanked QBTI molecule confirmed that the quinoidal structure contributed to the high planarity of the molecular skeleton and the construction of one‐dimensional stacks. The quinoidal form of bisthienoisatin derivatives displayed ambipolar carrier transport properties with mobilities of approximately 10−4 cm2 V−1 s−1. Different flanking aromatic rings considerably affected the thin‐film microstructure and hence the charge carrier transport properties of the material. The QBTI‐based narrow energy gap polymers were theoretically designed and synthesized. Delocalized quinoidal resonance of QBTI unit along the polymer backbone is of particular importance to achieve relatively high conductive state (10−3 S cm−1). We demonstrate that QBTI cores should be promising building blocks for constructing narrow energy gap semiconducting and conductive polymers.

Simplified interconnection structure based on C60/SnO2-x for all-perovskite tandem solar cells

The efficiencies of all-perovskite tandem devices are improving quickly. However, their complex interconnection layer (ICL) structures—with typically four or more layers deposited by different processes—limit their prospects for applications. Here, we report an ICL in all-perovskite tandem cells consisting merely of a fullerene layer and a SnO2–x (0 < x < 1) layer. The C60 layer is unintentionally n-doped by iodine ions from the perovskite and thus acts as an effective electron collecting layer. The SnO2–x layer, formed by the incomplete oxidization of tin (x = 1.76), has ambipolar carrier transport property enabled by the presence of a large density of Sn2+. The C60/SnO1.76 ICL forms Ohmic contacts with both wide and narrow bandgap perovskite subcells with low contact resistivity. The ICL boosts the efficiencies of small-area tandem cells (5.9 mm2) and large-area tandem cells (1.15 cm2) to 24.4% and 22.2%, respectively. The tandem cells remain 94% of its initial efficiency after continues 1-sun illumination for 1,000 h. Interconnecting layers are critical to the efficiency of tandem solar cells and a high number of layers is typically needed to ensure good electrical properties. Yu et. al show that a fullerene/tin-oxide interconnecting layer enables 24.4% efficiency and improved stability in all-perovskite tandem solar cells.

Electrochemical Stability and Ambipolar Charge Transport in Diketopyrrolopyrrole-Based Organic Materials

An important strategy for realizing flexible complementary circuits with organic semiconductors is to achieve balanced ambipolar charge transport properties with reduced anisotropy. Here, we presen...

Precise Positioning of Organic Semiconductor Single Crystals with Two-Component Aligned Structure through 3D Wettability-Induced Sequential Assembly.

Highly ordered organic semiconductor single-crystal (OSSC) arrays are ideal building blocks for functional organic devices. However, most of the current methods are only applicable to fabricate OSSC arrays of a single component, which significantly hinders the application of OSSC arrays in integrated organic circuits. Here, we present a universal approach, termed three-dimensional (3D) wettability-induced sequential assembly that can programmatically and progressively manipulate the crystallization locations of different organic semiconductors at the same spatial position using a 3D microchannel template, for the fabrication of the two-component OSSC arrays. As an example, we successfully prepared two-component, bilayer structured OSSC arrays consisting of n-type N,N'-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide and p-type 6,13-bis(triisopropylsilylethynyl)pentacene microbelts. The bicomponent OSSCs show ambipolar carrier transport properties with hole and electron mobilities of 0.342 and 0.526 cm2 V-1 s-1, respectively. Construction of complementary inverters is further demonstrated based on the two-component OSSCs. The capability of integration of multicomponent OSSC arrays opens up unique opportunities for future high-performance organic complementary circuits.

Ambipolar thin-film transistors based on organic semiconductor blend

Abstract Ambipolar thin-film transistors are fabricated employing p-channel (2-decyl-7-phenylbenzo[b]benzo [4,5]thieno[2,3-d]thiophene; Ph-BTBT-C10) and n-channel (N,N'-di-n-octyl-3,4,9,10-perylenetetracarboxylic diimide; PTCDI-C8) semiconductors in bilayer and bulk heterojunction architecture. Bilayer organic semiconductors with small thickness of the first layer exhibit ambipolar device characteristics with relatively poor electrical performance. On the other hand, bulk heterojunction organic thin-film transistors (OTFTs) with optimized blend ratio exhibited higher ambipolar charge transport properties with carrier mobility as high as 0.22 and 0.038 cm2 V−1s−1 for hole and electron, respectively. Complementary-like inverters fabricated based on optimized bulk heterojunction OTFTs show high transfer gain of 96.

Theoretical Investigations into the Electron and Ambipolar Transport Properties of Anthracene-Based Derivatives.

To obtain anthracene-based derivatives with electron transport behavior, two series of anthracene-based derivatives modified by trifluoromethyl groups (-CF3) and cyano groups (-CN) at the 9,10-positions of the anthracene core were studied. Their electronic structures and crystal packings were also analyzed and compared. The charge-carrier mobilities were evaluated by quantum nuclear tunneling theory based on the incoherent charge-hopping model. Our results suggest that introducing -CN groups at 9,10-positions of the anthracene core is more favorable than introducing -CF3 to maintain great planar rigidity of the anthracene skeleton, decreasing more lowest unoccupied molecular orbital energy levels (0.45-0.55 eV), reducing reorganization energies, and especially forming a tight packing motif. Eventually, the excellent electron transport materials could be obtained. The molecule 1-B in Series 1 containing -CF3 groups is an ambipolar organic semiconductor (OSC) material with a 2D transport network, and its value of μh-max/μe-max is 1.75/0.47 cm2 V-1 s-1 along different directions; 2-A and 2-C in Series 2 with -CN groups are excellent n-type OSC candidates with the maximum intrinsic mobilities of 3.74 and 2.69 cm2 V-1 s-1 along the π-π stacking direction, respectively. Besides, the Hirshfeld surface and quantum theory of atoms in molecules analyses were applied to reveal the relationship between noncovalent interactions and crystal stacking.