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The doping levels of conjugated polymers significantly influence their conductivity, energetics, and optical properties. Recently, a highly conductive n‐doped polymer called poly (3,7‐dihydrobenzo[1,2‐b:4,5‐b′]difuran‐2,6‐dione) (poly(benzodifurandione), n‐PBDF) is discovered, opening new possibilities for n‐type conducting polymers in printed electronics and other fields. Controlling the doping level of n‐PBDF is of great interest due to its wide range of potential applications. Here controlled dedoping and redoping of n‐PBDF is reported and a mechanistic understating of such a process is provided. Dedoping occurs through electron transfer and proton capture, wherein the ionic dopants, tris(4‐bromophenyl)ammoniumyl hexachloroantimonate (Magic Blue), exhibit efficient proton capture ability and stronger interaction with n‐PBDF, resulting in high dedoping efficiency. Moreover, chemically dedoped PBDF can be redoped using various proton‐coupled electron transfer agents. By manipulating the doping levels of n‐PBDF thin films, ranging from highly doped to dedoped states, the system demonstrates controllable conductivity in five orders of magnitude, adjustable optical properties, and energetics. As a result, these characteristics demonstrate the potential applications of n‐PBDF in organic electrochemical transistors and thermoelectrics. [ABSTRACT FROM AUTHOR]

2D MoTe2 is regarded as a favorable candidate for semiconductor nanoelectronics integration. Chemical‐vapor‐deposition‐grown MoTe2 usually presents p‐type characteristics. In order to realize basic electronic units like complementary metal‐oxide‐semiconductor (CMOS) inverter, controllable fabrication of p‐ and n‐type transistors at large scale is of vital importance. Here, large‐scale MoTe2 n‐channel field‐effect transistor (n‐FET) arrays are successfully fabricated with seamless coplanar metallic 1T′‐WTe2 contacts to reduce contact resistance. High‐k HfO2 serves as a gate dielectric and its atomic‐layer‐deposition (ALD) process causes an n‐doping effect on the 2H‐MoTe2 channel. The FETs perform typical n‐type characteristics with average electron density and on/off ratio of ≈1.7 × 1013 cm−2 and 2.1 × 104, respectively. Furthermore, large‐scale homogeneous CMOS inverter arrays are fabricated, showing clear logic swing with low power consumption (≈0.4 nW) and high device yield (≈92%). Notably, their voltage transfer characteristics exhibit small hysteresis, and they work well after being kept in air for 16 months, indicating high device stability. The statistical results show that both the n‐FETs and CMOS inverters have high uniformity and reliability in performance. Significantly, this fabrication method is free from transfer processes and compatible with traditional silicon technology. This work paves the way for the application of few‐layer MoTe2 in semiconductor nanoelectronics integration. [ABSTRACT FROM AUTHOR]

Abstract 2D MoTe2 is regarded as a favorable candidate for semiconductor nanoelectronics integration. Chemical‐vapor‐deposition‐grown MoTe2 usually presents p‐type characteristics. In order to realize basic electronic units like complementary metal‐oxide‐semiconductor (CMOS) inverter, controllable fabrication of p‐ and n‐type transistors at large scale is of vital importance. Here, large‐scale MoTe2 n‐channel field‐effect transistor (n‐FET) arrays are successfully fabricated with seamless coplanar metallic 1T′‐WTe2 contacts to reduce contact resistance. High‐k HfO2 serves as a gate dielectric and its atomic‐layer‐deposition (ALD) process causes an n‐doping effect on the 2H‐MoTe2 channel. The FETs perform typical n‐type characteristics with average electron density and on/off ratio of ≈1.7 × 1013 cm−2 and 2.1 × 104, respectively. Furthermore, large‐scale homogeneous CMOS inverter arrays are fabricated, showing clear logic swing with low power consumption (≈0.4 nW) and high device yield (≈92%). Notably, their voltage transfer characteristics exhibit small hysteresis, and they work well after being kept in air for 16 months, indicating high device stability. The statistical results show that both the n‐FETs and CMOS inverters have high uniformity and reliability in performance. Significantly, this fabrication method is free from transfer processes and compatible with traditional silicon technology. This work paves the way for the application of few‐layer MoTe2 in semiconductor nanoelectronics integration.

Surface charge transfer doping (SCTD) is an alternative approach to achieving n-type doped diamonds since the n-type bulk doping of diamonds remains a challenge, but so far efficient diamond n-type SCTD has not been achieved. Here we provide a comprehensive study of the n-type SCTD of the diamond by using first-principles calculations based on the density functional theory. Taking the principle that ionization potentials of the dopants must be higher than those of the diamond, we screened a series of molecules that may be suitable for diamond n-type SCTD doping. Methyl viologen and benzyl viologen provide the largest amount of transfer electron among the common n-type SCTD dopants for the oxygen and fluorine terminated (100) surface diamond, with the electron areal densities of 2.60 × 10 13 cm − 2 and 9.20 × 10 12 cm − 2 , respectively. It is indicated that the transferred electron amount is positively correlated with the difference between the ionization potentials of the dopants and the electron affinity of the diamond, while the density of dopants also has a positive impact with a decreasing trend. The present work provides a useful understanding of the physical mechanism for the n-type SCTD of diamonds, and benefits the development of n-type SCTD diamond materials. [ABSTRACT FROM AUTHOR]

In this work, enzymatic doped/undoped poly-silicon nanowire sensors with different lengths were fabricated using a top-down technique to measure glucose concentration. The sensitivity and resolution of these sensors correlate well with the dopant property and length of nanowire. Experimental results indicate that the resolution is proportional to the nanowire length and dopant concentration. However, the sensitivity is inversely proportional to the nanowire length. The optimum resolution can be better than 0.02 mg/dL for a doped type sensor with length of 3.5 μm. Furthermore, the proposed sensor was demonstrated for 30 applications with similar current-time response and showed good repeatability. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotube (SWNT) is desirable next generation semiconductor for flexible, transparent and even stretchable with exceptional electrical characteristics. Here, high-performance n-type semiconducting SWNT field-effect transistors (s-SWNT-FETs) are achieved by chemical doping using anion-π interaction between SWNT and anion of tetrabutylammonium fluoride (TBAF) salt. The Fermi level (E F) of SWNT shifts to the conduction band edge with increasing dopant concentration. The doped s-SWNT-FETs exhibit significant improvement in electron mobility (39.4 cm2V−1s−1) with high current on/off ratio (>104) compared to those of un-doped device. The doping using anion–π interaction leads to populate electron density of channel and reduces both channel and contact resistance by 99.0% and 99.6%. Excess carriers introduced by the doping compensate traps by shifting the E F toward conduction band edge. The doped device showed improved current stability after 10 h of bias stress test, while the current of undoped FET decreased by 40.4%. Finally, flexible FETs with TBAF doped s-SWNT network are demonstrated on polyethylene naphthalate substrate and show stable operation after 2000 times bending test. [Display omitted] [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are considered to be promising building blocks for the next generation electronic and optoelectronic devices. Various doping schemes and work function engineering techniques have been explored to overcome the intrinsic performance limits of 2D TMDs. However, a reliable and long-time air stable doping scheme is still lacking in this field. In this work, we utilize keV ion beams of H2+ to irradiate layered WSe2 crystals and obtain efficient n-type doping effect for all irradiated crystals within a fluence of 1 × 1014 protons·cm−2 (1e14). Moreover, the irradiated WSe2 remains an n-type semiconductor even after it is exposed to ambient conditions for a year. Localized ion irradiation with a focused beam can directly pattern on the sample to make high performance homogenous p-n junction diodes. Raman and photoluminescence (PL) spectra demonstrate that the WSe2 crystal lattice stays intact after irradiation within 1e14. We attribute the reliable electron-doping to the significant increase in Se vacancies after the proton irradiation, which is confirmed by our scanning transmission electron microscope (STEM) results. Our work demonstrates a reliable and long-term air stable n-type doping scheme to realize high-performance electronic TMD devices, which is also suitable for further integration with other 2D devices. [ABSTRACT FROM AUTHOR]

Achieving efficient doping in n-type conjugated polymers is crucial for their application in electronic devices. In this study, an n-type doping method is developed based on cation exchange that maintains a high doping level while ensuring a high degree of structural order, leading to significantly improved electrical conductivity. By investigating various dopants and ionic liquids, it is discovered that the choice of dopant influences doping efficiency, while the selection of ionic liquid affects cation exchange efficiency. Through careful selection of suitable dopants and ionic liquids, High doping levels are achieved remarkably in a short period, resulting in the highest conductivity (nearly 1 × 10 - 2 ¹) compared to other doping methods for poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (N2200). The findings highlight the robustness and efficiency of cation exchange doping as an effective approach for achieving high-quality n-type doping in conjugated polymers, thereby opening new avenues for the development of advanced polymer-based electronic devices.- ¹) compared to other doping methods for poly{[N,N'-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5'-(2,2'-bithiophene)} (N2200). The findings highlight the robustness and efficiency of cation exchange doping as an effective approach for achieving high-quality n-type doping in conjugated polymers, thereby opening new avenues for the development of advanced polymer-based electronic devices., (© 2024 Wiley‐VCH GmbH.)

The development of n-type organic semiconductors (OSCs) has been lagged behind that of p-type OSCs, mainly due to the limited availability of the electron deficient π-conjugated backbones and facile electron trapping by ambient oxidants. Improving the performance of n-type OSCs through n-doping is essential for realizing p-n junction diodes and complementary circuits. Conventional vacuum deposition doping is costly and time-consuming, while solution doping risks thermal damage through necessary annealing. Therefore, the development of a simpler, more affordable n-doping method is crucial. In this study, we have developed a solution-processed n-doping method using an organic cationic dye in a low boiling point solvent that can be dried at room temperature in 1 h, which eliminates the need for annealing. The effects of different organic cationic dyes and reducing agents on the n-type OSC were evaluated. After n-doping, electron mobility and photoresponsivity in the sample increased by 5.5 and 20 times, respectively, compared to undoped samples. Furthermore, there was no significant degradation in the electron mobility of the n-doped samples under ambient conditions after 15 days. Studying n-doping with various organic cationic dyes in different OSC materials, embracing further research into their applications and mechanisms, would advance the field of organic electronics.

Most near‐infrared (NIR) light‐responsive photocatalysts inevitably suffer from low charge separation due to the elevated Coulomb interaction between electrons and holes. Here, an n‐type doping strategy of alkaline earth metal ions is proposed in crystalline K+ implanted polymeric carbon nitride (KCN) for visible and NIR photoactivity. The n‐type doping significantly increases the electron densities and activates the n→π* electron transitions, producing NIR light absorption. In addition, the more localized valence band (VB) and the regulation of carrier effective mass and band decomposed charge density, as well as the improved conductivity by 1–2 orders of magnitude facilitate the charge transfer and separation. The proposed n‐type doping strategy improves the carrier mobility and conductivity, activates the n→π* electron transitions for NIR light absorption, and breaks the limitation of poor charge separation caused by the elevated Coulomb interaction. [ABSTRACT FROM AUTHOR]

Abstract Most near‐infrared (NIR) light‐responsive photocatalysts inevitably suffer from low charge separation due to the elevated Coulomb interaction between electrons and holes. Here, an n‐type doping strategy of alkaline earth metal ions is proposed in crystalline K+ implanted polymeric carbon nitride (KCN) for visible and NIR photoactivity. The n‐type doping significantly increases the electron densities and activates the n→π* electron transitions, producing NIR light absorption. In addition, the more localized valence band (VB) and the regulation of carrier effective mass and band decomposed charge density, as well as the improved conductivity by 1–2 orders of magnitude facilitate the charge transfer and separation. The proposed n‐type doping strategy improves the carrier mobility and conductivity, activates the n→π* electron transitions for NIR light absorption, and breaks the limitation of poor charge separation caused by the elevated Coulomb interaction.

In this work, enzymatic doped/undoped poly-silicon nanowire sensors with different lengths were fabricated using a top-down technique to measure glucose concentration. The sensitivity and resolution of these sensors correlate well with the dopant property and length of nanowire. Experimental results indicate that the resolution is proportional to the nanowire length and dopant concentration. However, the sensitivity is inversely proportional to the nanowire length. The optimum resolution can be better than 0.02 mg/dL for a doped type sensor with length of 3.5 μm. Furthermore, the proposed sensor was demonstrated for 30 applications with similar current-time response and showed good repeatability.

We investigated the photoluminescence (PL) properties of heavily Sb doped n+-Ge1âˆ' x Sn x layers and demonstrated the formation of a double heterostructure (DHS) for the n+-Ge1âˆ' x Sn x active layer. A single PL peak was observed for n+-Ge1âˆ' x Sn x layers thicker than 80 nm with increasing the Sb concentration up to 1020 cmâˆ'3, attributed to the superior crystallinity and pseudo-direct bandgap transition mechanism, while a 15 nm thick n+-Ge1âˆ' x Sn x layer did not exhibit PL signals. A favorable heterostructure for n+-Ge1âˆ' x Sn x is proposed from the viewpoint of the increased valence band offset (Î" E v) using n-Si y Ge1âˆ' y as the cladding layer. We demonstrated the formation of an n-Si y Ge1âˆ' y (15 nm)/n+-Ge1âˆ' x Sn x (15 nm)/n-Si y Ge1âˆ' y (15 nm) DHS with a superior crystallinity and high PL peak intensity comparable to that of a thick n+-Ge1âˆ' x Sn x . We discuss the reasons for the PL performance improvement by forming the DHS, including the sufficient carrier confinement and the suppression of surface recombination. [ABSTRACT FROM AUTHOR]

Transparent conductive electrodes (TCEs) are fundamental components for designing flexible electronics and displays. TCEs should exhibit high electrical conductivity, optical transparency, mechanical flexibility, and a suitable work function (WF) for efficient performance. Because of their unique mechanical, electrical, and optical properties, sparse single-wall carbon nanotube (SWCNT) networks are attractive candidates for TCEs. However, to achieve a highly conductive sparse network, a reduction of the junctions' resistances between the SWCNTs is required. In addition, SWCNTs inherently possess a high WF, which is fundamental for functional anodes but not suitable for cathodes. In this work, n-type doping of SWCNTs via coordinative bonding of triethylenetetramine (TETA) to their surface is introduced to tune both the WF and the junctions' resistance. A self-developed conductive atomic force microscopy (cAFM) technique is used to investigate the same individual junctions in SWCNT networks before and after exposure to TETA fumes and post heating. The mechanisms by which TETA doping modifies the "global" properties of SWCNT networks are studied by Kelvin probe microscopy, X-ray photoemission spectroscopy (XPS), Raman spectroscopy, and ultraviolet–visible spectroscopy. Following TETA doping, improved conductivity and reduced WF are achieved, implying n-type charge-transfer doping. These results provide a significant step toward the use of SWCNTs as transparent cathodes in organic-based electronic devices. [ABSTRACT FROM AUTHOR]

Doped conjugated organic semiconductors are suitable materials to be used as building blocks of flexible and cost‐effective thermoelectric generators. While several efficient solution‐processable p‐type organic thermoelectric materials are reported, n‐doped materials are fewer because of lack of good electron‐transporting materials and stable n‐dopants. Here, n‐doping process is investigated on a relevant n‐type class, namely naphthalene‐diimide‐based copolymers. Among these, copolymer incorporating bithiophene (T2) donor units, largely studied poly{N,N″‐bis(2‐octyl‐dodecyl)‐1,4,5,8‐naphthalenedicarboximide‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)} (PNDI‐T2), is one of first polymers reported to achieve good solution‐based n‐doping. By substituting T2 with thienylenevinylene‐thienylene (TVT), resulting PNDI‐TVT copolymer exhibits improvements on both structural and transport properties, offering a suitable basis to improve thermoelectric properties upon doping. When doped with 1H‐benzimidazoles, PNDI‐TVT achieves maximum in‐plane electrical conductivity at room temperature of 2.4 × 10−2 S cm−1, being the highest value for PNDI‐T2 solution‐doped derivatives excluding those with oligoethylene‐glycol chains. Electron paramagnetic resonance and variable temperature electrical conductivity measurements relate this enhancement to more efficient charge‐transfer between n‐dopant molecules and host polymeric matrix, and easier charge carrier transport within the system. This electrical conductivity large enhancement also improves in‐plane power factor of almost three times with respect to similar doped PNDI‐T2 films. [ABSTRACT FROM AUTHOR]

Conjugated polymers with ethylene glycol-type side chains are commonly used as channel materials in organic electrochemical transistors (OECTs). To improve the performance of these materials, new chemical structures are often created through synthetic routines. Herein, we demonstrate that the OECT performance of these polymers can also be improved by changing their density-of-state (DOS) profile through solvent engineering. Depending on the solvent polarity, it solvates the backbone and side chains of the conjugated polymer differently, leading to differences in molecule orientation, π-stacking paracrystallinity, and film defects, such as grain boundaries and pinholes. This then results in a change in the DOS profile of the polymer. A more intense and narrow-width DOS distribution is usually observed in organic films with an "edge on" orientation and fewer film defects, while films with a "face on" orientation and apparent defects show a broadened DOS profile. The OECT devices that use the polymer film with a more intense and narrow-width DOS profile exhibit a better-normalized transconductance and figure-of-merit μC* than those with a broadened DOS profile (0.74 to 4.29 S cm -1 and 3.5 to 14.3 F cm -1 V -1 s -1 ). This study provides useful insights into how the DOS profile affects the mixed ionic-electronic conduction performance and presents a new avenue for improving n-type OECT materials.

Photodriven nonoxidative coupling of CH4 (NOCM) is an attractive potential way to use abundant methane resources. Herein, an n‐type doped photocatalyst for NOCM is created by doping single‐atom Nb into hierarchical porous TiO2–SiO2 (TS) microarray, which exhibits a high conversion rate of 3.57 μmol g−1 h−1 with good recyclability. The Nb dopant replaces the 6‐coordinated titanium on the (1 0 1) plane and forms shallow electron‐trapped surface polarons along [0 1 0] direction and the comparison of different models proves that the electron localization caused by the n‐type doping is beneficial to both methane activation and ethane desorption. The positive effect of n‐type dopant on CH4 conversion is further verified on Mo‐, W‐ and Ta‐doped composites. In contrast, the doping of p‐type dopant (Ga, Cu, Fe) shows a less active influence. [ABSTRACT FROM AUTHOR]

Herein, a technological process for the fabrication of n‐type doped V‐shaped structures on (100) single‐crystalline diamond substrates, designed to overcome the limitations of n‐type doping on (100) surfaces, is presented. This doping enhancement process can be applied to realize electronic power devices such as a junction barrier Schottky diode or junction field effect transistors with low on‐resistance. Herein, a catalytic etching process is performed by using square‐shaped nickel masks on the diamond surface and annealing in a hydrogen atmosphere, resulting in the formation of inverted pyramidal structures with flat {111} sidewalls. The resulting V‐shaped structures are subsequently overgrown with phosphorus‐doped diamond to achieve n‐type doped facets with higher doping concentrations. Cathodoluminescence studies reveal the predominant incorporation of phosphorus donors on the {111} sidewalls of V‐shaped structures. [ABSTRACT FROM AUTHOR]

Monolayer transition-metal dichalcogenides MX2 (M = Mo, W; X = S, Se, Te) have attracted much attention for use in electronic and optical applications. Due to their sensitivity to gases, the surface of these materials has been protected by coating with polymers such as polyethyleneimine (PEI). However, the effects of such coating layers on the electronic and optical properties of MX2 are not well understood. In this work, density functional theory calculations are used to study the effects of adsorption of PEI on monolayer MX2 substrates based on the electronic and optical properties before and after PEI adsorption. The results show that the bandgap of the substrate decreases significantly upon PEI adsorption, while the optical spectra show only slight modification with a decrease of intensity at short wavelengths around 300 nm. The results also indicate that PEI adsorption results in n-type doping states in MX2 but does not deteriorate the optical properties in the visible range. [ABSTRACT FROM AUTHOR]

• Cs-decorated ZnO surfaces with high-conductivity and low work function are suitable as PETE anode materials. • The n-type doping and Cs adsorption process on ZnO (0001) surface are discussed. • The optimum Cs adsorption site and coverage are determined. • The [Cs-ZnO] dipole moment model can explain the variation mechanism of work function on Cs-covered surfaces. • The conversion efficiency of PETE devices with ZnO as anode material is predicted. Using first-principles calculation method, we investigate the possibility of Si-doped ZnO(0001) surface with Cs coating layer applied as the anode material of solar cell based on photon-enhanced thermionic emission (PETE) mechanism. The n-type doping and Cs adsorption process on ZnO(0001) surface are systematically discussed and analyzed. For n-type doping, five Si substitution doping models are established to study the effects of different doping sites on the formation energy, density of state and work function of n-type ZnO (0001) surfaces. Due to the lowest formation energy, the Site-2 doping model with Si replacing the Ga atom at the third bilayer is selected as the Cs adsorption substrate. Moreover, the optimum Cs adsorption site and coverage on Si-doped ZnO (0001) surface are respectively determined. Meanwhile, excessive Cs adsorption will lead to the appearance of "Cs poisoning" phenomenon. The [Cs-ZnO] dipole moment model can be employed to explain the variation mechanism of work function on Cs-covered surfaces. Based on PETE photoemission theory, the conversion efficiency of PETE devices with ZnO as anode material is predicted. These results provide guidelines for the design of PETE anode materials with high-conductivity and low work function. [ABSTRACT FROM AUTHOR]

We report calculated energetics (at the GGA, and at the B3LYP, HSE06 hybrid density functional levels of theory) and electronic properties (B3LYP, HSE06) of Li and N co-doped diamond containing LiN x clusters (x = 1–4). Defect energies and structural properties at the GGA and hybrid (B3LYP, HSE06) levels of theory are very similar. Our results for isolated Li and N dopants agree with previous work in that they are not suitable candidates for shallow n-type donors. Here, we investigate the effects of addition of N atoms as a co-dopant with Li, which vary with the Li:N ratio and whether Li is interstitial or substitutional. Reaction energies, geometries, bonding and densities of states (DOS) are examined. Nitrogen stabilises substitutional rather than interstitial lithium. Atom-projected DOS show that the chief contributions to the defect states are not from orbitals on the dopant atoms themselves but from states associated with neighbouring carbon atoms. Only the tetrahedral 1:4 cluster, Li C N 4 , with substitutional Li is likely to behave as a shallow donor. We propose a non-molecular synthetic route for preparation of the Li C N 4 -doped material via prior generation of the N 4 V centre at temperatures at which Li is mobile but Li C N 4 clusters are not. Image 1 [ABSTRACT FROM AUTHOR]

Doping provides an efficient strategy to control the electronic properties of organic semiconductors. However, compared with the widely reported p‐type doping protocols, n‐type doping of organic semiconductors still remains a challenge. Herein, a series of novel n‐doped conjugated polyelectrolytes (CPEs) with high doping levels and conductivity are designed. These CPEs are synthesized via a facile, metal‐free, and high‐yield aldol condensation protocol from bis‐isatin and bis‐oxindole monomers. The designed CPEs possess a n‐type electron‐deficient and rigid conjugated backbone, resulting in easy charge delocalization, enhanced n‐doping behaviors, and high conductivity. The evolution on the counterions of these CPEs further alters their n‐doping behaviors, charge transporting properties, and work function tunability, etc. By using these CPEs as electron transport materials (ETMs) for nonfullerene polymer solar cells (NF–PSCs), high power conversion efficiencies (PCEs) over 16% can be achieved when PM6:Y6 is used as the active component. Moreover, these CPEs can enable efficient NF–PSCs even if their thicknesses are up to 60 nm, indicating the potential of these CPEs as thickness‐insensitive ETMs for the fabrication of large‐area NF–PSCs. [ABSTRACT FROM AUTHOR]

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This study focuses on the fabrication of nanocomposite thermoelectric devices by blending either a naphthalene-diimide (NDI)-based conjugated polymer (NDI-T1 or NDI-T2), or an isoindigo (IID)-based conjugated polymer (IID-T2), with single-walled carbon nanotubes (SWCNTs). This is followed by sequential process doping method with the small molecule 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI) to provide the nanocomposite with n-type thermoelectric properties. Experiments in which the concentrations of the N-DMBI dopant are varied demonstrate the successful conversion of all three polymer/SWCNT nanocomposites from p-type to n-type behavior. Comprehensive spectroscopic, microstructural, and morphological analyses of the pristine polymers and the various N-DMBI-doped polymer/SWCNT nanocomposites are performed in order to gain insights into the effects of various interactions between the polymers and SWCNTs on the doping outcomes. Among the obtained nanocomposites, the NDI-T1/SWCNT exhibits the highest n-type Seebeck coefficient and power factor of -57.7 µV K -1 and 240.6 µW m -1 K -2 , respectively. However, because the undoped NDI-T2/SWCNT exhibits a slightly higher p-type performance, an integral p-n thermoelectric generator is fabricated using the doped and undoped NDI-T2/SWCNT nanocomposite. This device is shown to provide an output power of 27.2 nW at a temperature difference of 20 K., (© 2023 Wiley-VCH GmbH.)

Epitaxial growth of n-type semiconductor diamond films on (111)-oriented diamond has been achieved by hot-filament chemical vapor deposition (HFCVD) using a methane source and a trimethylphosphine dopant source. Secondary-ion mass spectrometry showed that the phosphorus atoms are incorporated into the films in the concentration range of 1018–1019 cm−3 from the vapor phase. Hall-effect measurements confirmed n-type conductivity in a wide temperature range up to 873 K. Electrons are thermally activated from a phosphorus donor level of approximately 0.57 eV as dominant carriers under the presence of tungsten atoms with concentrations of around 1018 cm−3 from filaments. These results indicate that HFCVD has the potential to be applied to an n-type doping process for fabricating diamond electronic devices in the phosphorus concentration range of not lower than 1018 cm−3. [ABSTRACT FROM AUTHOR]

The high quality p-Ga-03 single crystal doped with Si was grown by edge-defined film-fed grown (EFG) method with the doping concentration of 2 X 1018 cm--3. The crystal is light blue and the basic properties of the crystal were characterized by Laue diffraction, cathodoluminescence (CL) and Raman test. These characterisations show that the quality of the as-grown crystal is high. The bandgap is about 4. 71 eV obtained by ultraviolet transmittance spectrum. In addition, vertical Schottky diode was fabricated on the crystal by electron beam evaporation, lithography and development techniques. The average breakdown field strength £Ava of the Schottky diode is 2. 1 MV/cm and the on resistance is 3 mfl * cm2. Therefore, the simple device shows excellent performance. [ABSTRACT FROM AUTHOR]

The top-gated graphene field effect transistor (GFET) with electric-field induced doping polarity conversion has been demonstrated. The polarity of channel conductance in GFET can be transition from p-type to n-type through altering the gate electric field scanning range. Further analysis indicates that this complementary doping is attributed to the charge exchange between graphene and interface trap sites. The oxygen vacancies in Al2O3filmare are considered to be the origin of the trap sites. The trapping–detrapping process, which may be tuned by the electric field across the metal/oxide/graphene gate stack, could lead to the changing of the intrinsic electric property of graphene. This study promises to produce the complementary p- and n-type GFET for logic applications.

Pure and Al-doped (3 at.%) ZnO nanorods were prepared by two-step synthesis. In the first step, ZnO thin films were deposited on silicon wafers by spin coating; then, ZnO nanorods (NR) and Al-doped ZnO NR were grown using a chemical bath method. The structural properties of zincite nanorods were determined by X-ray diffraction (XRD) and corroborated well with the morphologic properties obtained by field-emission gun scanning electron microscopy (FEG SEM) with energy-dispersive X-ray spectroscopy (EDS). Morphology results revealed a minute change in the nanorod geometry upon doping, which was also visible by Kelvin probe force microscopy (KPFM). KPFM also showed preliminary electrical properties. Detailed electrical characterization of pure and Al-doped ZnO NR was conducted by temperature-dependent current–voltage (I–V) measurements on Au/(Al)ZnO NR/n-Si junctions. It was shown that Al doping increases the conductivity of ZnO NR by an order of magnitude. The I–V characteristics of pure and Al-doped ZnO NR followed the ohmic regime for lower voltages, whereas, for the higher voltages, significant changes in electric conduction mechanisms were detected and ascribed to Al-doping. In conclusion, for future applications, one should consider the possible influence of the geometry change of (Al)ZnO NRs on their overall electric transport properties.

Tungsten diselenide (WSe2) is attracting attention because of its superior electronic and optoelectronic properties. In recent years, the number of research works related to the WSe2‐based field‐effect transistors (FETs) has increased dramatically. Nonetheless, the performance of 2D WSe2 is influenced sensitively by metal–semiconductor (MS) interface states, where Fermi‐level pinning is substantial. This research explores Fermi‐level depinning by doping with an n‐type polymer. In this work, spin‐coated polyvinyl alcohol (PVA) is used as an n‐type dopant for achieving low‐contact‐resistance WSe2 FETs in cases of both high‐work‐function (Pd) and low‐work‐function (In) metals. Interestingly, the increase in the Schottky barrier height resulting from the application of PVA gives rise to Fowler–Nordheim tunneling for a doped Pd‐WSe2 contact. By contrast, only direct tunneling is observed for an In‐WSe2 contact irrespective of whether the dopant is used. The barrier‐height modification after doping reveals that the improvement of the contact resistance is correlated to the enhancement of tunneling current after doping, which is consistent with the measurement results. This work suggests a practical direction for contact engineering of future WSe2‐based electronic devices and expands the current understanding of charge transport at the MS contact when a polymeric n‐type dopant is applied. [ABSTRACT FROM AUTHOR]

The electronic and optical properties of InAs spherical quantum dot (QD) at the center of a doped n-type GaAs cylindrical nanowire were investigated by solving the Schrödinger and Poisson equations self consistently. The effect of donor density of a cylinder and the size of QD on the allowed energy levels, electrostatic potential, conduction bands and transition energy of the system were calculated. The optical properties related to intra-band transitions in the conduction band of this structure were studied through the compact density matrix approach. The results showed that the peak position and magnitude of optical absorption coefficients, which are mainly located in the far infrared region, and the refractive index changes were significantly affected by the incident optical intensity and the doping concentration of the surrounding media [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have been demonstrated as promising candidates for thermoelectrics (TEs) owing to their excellent electrical and mechanical properties. Here a new dopant to obtain flexible n‐type CNT‐based TE films from solution is reported. By doping single‐walled carbon nanotubes (SWCNTs) with tetrabutylammonium bromide (TBAB), p‐type nanotubes can be successfully converted to n‐type form, which is confirmed by both Raman and X‐ray photoemission spectroscopy (XPS) spectra. Furthermore, the influences of doping concentration and dispersion medium on TE properties are investigated. The optimal n‐type SWCNT films fabricated in N,N‐dimethylformamide (DMF) solvent exhibit an impressive power factor of 339 µW m−1 K−2 and excellent air stability by less than 10% variation of Seebeck coefficient during 192 h at room temperature without encapsulation, both of which are among the hitherto highest reported. This work sheds light on the interaction between TBAB molecules and SWCNTs in different dispersion media and offers a guideline for efficient n‐doping of SWCNT based TE materials. [ABSTRACT FROM AUTHOR]

As one common electron transport material for planar n‐i‐p perovskite solar cell, titanium dioxide (TiO2) compact layer has several challenging issues, such as surface hydroxyl groups, high defect density, and unmatched energy levels, causing severe energy loss and poor stability at contact. To solve these problems, the authors introduce a thin [6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM) interlayer doped with an air stable n‐type dopant, 3‐dimethyl‐2‐phenyl‐2,3‐dihydro‐1H‐benzoimidazole (DMBI) to modify the TiO2 surface. The state‐of‐the‐art characterizations demonstrate such modification significantly improves charge transfer at MAPbI3/TiO2 interface together with smaller energy level offset, leading to suppressed charge recombination. High‐quality perovskite film with larger crystal grain size grows on the n‐doped PCBM/TiO2 attributed to the better surface affinity. As a result, the average power conversion efficiency of perovskite solar cell exhibits a prominent improvement from 17.46% to 20.14%, with an enhancement in all device photovoltaic parameters. In addition, the stability of the device with n‐doped PCBM/TiO2 is much better than that of the control device with the bare TiO2 due to hydrophobicity nature of PCBM and low defect densities in the perovskite film and at the interface. This work indicates that many further device performance improvements should be conceivable by focusing on the perovskite interface. [ABSTRACT FROM AUTHOR]

To find potential n-type diamonds with shallow donor energy levels and low formation energies, the thermodynamic and electronic properties of Lithium-Boron (Li B) co-doped diamonds have been investigated using density functional theory (DFT) and hybrid density functional theory (HSE06). The structure, formation energy, electronic property and the potential synthesis pathway are analyzed. The results of the single Li defect is not a suitable candidate for a shallow n-type donor, as it distorts the diamond lattice and forms clusters, in agreement with previous work. The calculated ionization energy of Li i2 -B defect (0.29 eV) and the impurities formation energy (0.196 eV) is much lower than that of Li i defect. It suggests that the introduction of B helps improve the solubility of Li in diamond. Further structural analysis has shown that the incorporation of B atoms inhibits the diffusion of Li atoms and simultaneously reduces the internal strain in the diamond, resulting in a significant reduction in the distance between the two lithium atoms from 2.061 Å to 1.629 Å. At last, a non-molecular synthesis pathway of Li i2 -B co-doped diamond is proposed via prior generation of B-doped diamond at which Li atom is mobile which indicates there is a potential window-of-opportunity to prepare Li i2 -B co-doped diamond to achieve n-type diamond. [Display omitted] [ABSTRACT FROM AUTHOR]

For diamond with exceptional physical and chemical properties, it is a challenging task to develop an effective n -type dopant with satisfactory electronic properties. In this work, using the first-principles calculation, we report the n -type doping of diamond surface (areal electron density of 2.508 × 1013–4.090 × 1013 cm−2 and carrier mobility of 189–1186 cm2 V−1 s−1 at 298 K) by surface transfer doping using potassium (K). Electrons are transferred from the K atoms to the diamond surface, then electrons accumulation appears on the diamond surface. In addition, the areal electron density and electron affinity values increase with increasing K concentration. This work provides a new strategy for producing n -type diamond-based devices. [Display omitted] • Efficient surface n -type conductivity is obtained on diamond surface doped with K. • High areal electron density and carrier mobility at room temperature are achieved. • As the increase of K atoms, areal electron density and electron affinity increase. [ABSTRACT FROM AUTHOR]

Simultaneously achieving high efficiency and robust device stability remains a significant challenge for organic solar cells (OSCs). Solving this challenge is highly dependent on the film morphology of the bulk heterojunction (BHJ) photoactive blends; however, there is a lack of rational control strategy. Herein, it is shown that the molecular crystallinity and nanomorphology of nonfullerene-based BHJ can be effectively controlled by a squaraine-based doping strategy, leading to an increase in device efficiency from 17.26% to 18.5% when doping 2 wt% squaraine into the PBDB-TF:BTP-eC9:PC 71 BM ternary BHJ. The efficiency is further improved to 19.11% (certified 19.06%) using an indium-tin-oxide-free column-patterned microcavity (CPM) architecture. Combined with interfacial modification, CPM quaternary OSC excitingly shows an extrapolated lifetime of ≈23 years based on accelerated aging test, with the mechanism behind enhanced stability well studied. Furthermore, a flexible OSC module with a high and stable efficiency of 15.2% and an overall area of 5 cm 2 is successfully fabricated, exhibiting a high average output power for wearable electronics. This work demonstrates that OSCs with new design of BHJ and device architecture are highly promising to be practical relevance with excellent performance and stability., (© 2023 Wiley-VCH GmbH.)

Abstract Molybdenum diselenide (MoSe2) has attracted attention as a potential semiconductor platform. However, the as‐synthesized MoSe2 field‐effect transistors (FETs) tend to exhibit the arbitrary properties of n‐type, p‐type, or ambipolar behavior due to the uncontrolled growth condition. Here, two‐step functionalization is proposed to achieve n‐doping effect and long‐term stability in chemical vapor deposition (CVD)–grown MoSe2 FETs using oxygen plasma treatment followed by the deposition of an Al2O3 layer. After the two‐step surface functionalization procedure, three types of multilayer MoSe2 FETs are all converted to n‐type with the improvement of their electrical characteristics and stability; the n‐doped multilayer MoSe2 FETs exhibit an enhancement in field‐effect mobility from 12.23 to 31.57 cm2 V−1 s−1 and a 3 times higher Ion/Ioff, compared to pristine multilayer MoSe2 FETs. This enhancement of electric performance is attributed to the oxidation of topmost MoSe2 to interfacial MoOx with SeOx induced by the oxygen plasma treatment, as well as to the existence of fixed positive charges in deposited Al2O3. The functionalized devices exhibit excellent stability against stress, as confirmed with negative bias illumination stress tests for 7200 s. Moreover, an environmental stability test for 21 days reveals no degradation in electric performance of MoSe2 FETs.

The development of n-type single-walled carbon nanotubes (SWCNTs) stable under an air atmosphere is a key issue to prepare an efficient and stable thermoelectric conversion device using SWCNTs. Doping of SWCNT sheets with 2-(2- methoxyphenyl)-1,3-dimethyl-2,3-dihydro-1H- benzo-[d]-imidazole (o-MeO-DMBI) offers air-stable n-type SWCNT sheets. However, a clear mechanism of the stabilization in air has not been clarified yet. In this study, air stability is found to largely depend on the doping concentration. Adsorption isotherm experiments of the dopant onto SWCNT sheet reveal that the entire coverage of the SWCNT surface by o-MeO-DMBI cation is the key requirement to realize the air stability, which is well-supported by the theoretical calculation. This finding provides useful guidelines to develop air-stable n-type SWCNTs with various n-dopants. [ABSTRACT FROM AUTHOR]

Abstract Despite intensive studies on perovskite solar cells (PSCs) by employing graphene transparent conductive electrodes (GR TCEs), no use of n-type GR as a TCE has been reported for PSCs. It is known to be technologically more easy to prepare p-type GR TCEs than n-type ones because even pristine GR usually exhibits p-type characteristics in air. P-type GR can be employed in p-i-n- type PSCs as a TCE, but not in n-i-p- type ones. In addition, most of the p-i-n- type structures are not suitable for flexible substrates due to the inherent high-temperature annealing process. Here, n-type (Ag nanowires-doped) GR TCEs are first used for n-i-p CH 3 NH 3 PbI 3 (MAPbI 3) PSCs. With increasing the doping concentration (n A) of Ag nanowires to 0.3 wt%, the sheet resistance (R s) and transmittance (T) of the TCE monotonically decrease to ∼52 Ω/sq and ∼90%, respectively. Due to the n A -dependent trade-off relation between the R s and the T, the DC conductivity/optical conductivity ratio is the largest (∼62) at n A = 0.1 wt%, resulting in maximum power conversion efficiencies (PCEs) of 15.80 and 13.45% for the PSCs on rigid and flexible substrates, respectively, indicating PCE enhancements more than 50 and 30% by using the n-type GR TCEs. Highlights • First use of n-type-graphene electrodes for n-i-p perovskite solar cells. • Power conversion efficiencies (PCEs) of 13.45% on flexible substrates. • Excellent stability maintaining ∼94% of initial PCE after bending. [ABSTRACT FROM AUTHOR]

Abstract Perovskite solar cells are promising photovoltaic devices with high efficiency beyond 23%, but thermal instability is one of the key obstacles for the commercialization. To prolong thermal stability, (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl) phenyl)dimethylamine is doped into a state-of-the-art fullerene derivative with a hydrophilic triethylene glycol type side chain as electron transport layer in planar perovskite cells with low-temperature process (<100 °C). The addition of dopant in electron transport layer results in stable layered structure. We observe that the increase of electron transport layer conductivity and optimized reduction of work function facilitate charge extraction and improve the energy level alignment. As a result, CH 3 NH 3 PbI 3 -based n-i-p perovskite cells with doped electron transport layer exhibit a hysteresis-free power conversion efficiency of 18.5%, outperforming the ones based on pristine electron transport layer (16.2%) or the other fullerene derivatives. Strikingly, the corresponding unsealed devices in air show long-term thermal stability. Devices sustain 85% of their initial efficiency after 1000 h storage under 60 °C. Our work bodes well for the dawn of commercialization of perovskite devices, providing the chance for the exploration of such high-efficiency devices with long-term thermal stability on flexible substrates. Graphical abstract Image 1 Highlights • Deposited doped PTEG-1 is not required thermally annealing. • The doped PTEG-1 self-assembled into stable layered structure. • CH 3 NH 3 PbI 3 -based n-i-p cells exhibit a PCE of 18.5%. • Devices sustain 85% of initial efficiency after 1000 h under 60 °C. [ABSTRACT FROM AUTHOR]

Molybdenum diselenide (MoSe2) has attracted attention as a potential semiconductor platform. However, the as-synthesized MoSe2 field-effect transistors (FETs) tend to exhibit the arbitrary properties of n-type, p-type, or ambipolar behavior due to the uncontrolled growth condition. Here, two-step functionalization is proposed to achieve n-doping effect and long-term stability in chemical vapor deposition (CVD)-grown MoSe2 FETs using oxygen plasma treatment followed by the deposition of an Al2O3 layer. After the two-step surface functionalization procedure, three types of multilayer MoSe2 FETs are all converted to n-type with the improvement of their electrical characteristics and stability; the n-doped multilayer MoSe2 FETs exhibit an enhancement in field-effect mobility from 12.23 to 31.57 cm2 V-1 s-1 and a 3 times higher Ion/Ioff, compared to pristine multilayer MoSe2 FETs. This enhancement of electric performance is attributed to the oxidation of topmost MoSe2 to interfacial MoOx with SeOx induced by the oxygen plasma treatment, as well as to the existence of fixed positive charges in deposited Al2O3. The functionalized devices exhibit excellent stability against stress, as confirmed with negative bias illumination stress tests for 7200 s. Moreover, an environmental stability test for 21 days reveals no degradation in electric performance of MoSe2 FETs. [ABSTRACT FROM AUTHOR]

The realization of a fully integrated group IV electrically driven laser at room temperature is an essential issue to be solved. We introduced a novel group IV side-emitting laser at a wavelength of 1550 nm based on a 3-layer Ge/Si quantum well (QW). By designing this scheme, we showed that the structural, electronic, and optical properties are excited for lasing at 1550 nm. The preliminary results show that the device can produce a good light spot shape convenient for direct coupling with the waveguide and single-mode light emission. The laser luminous power can reach up to 2.32 mW at a wavelength of 1550 nm with a 300-mA current. Moreover, at room temperature (300 K), the laser can maintain maximum light power and an ideal wavelength (1550 nm). Thus, this study provides a novel approach to reliable, efficient electrically pumped silicon-based lasers.

Controlled doping with an effective carrier concentration higher than 1020 cm−3 is a key challenge for the full integration of Ge into silicon-based technology. Such a highly doped layer of both p- and n type is needed to provide ohmic contacts with low specific resistance. We have studied the effect of ion implantation parameters i.e., ion energy, fluence, ion type, and protective layer on the effective concentration of electrons. We have shown that the maximum electron concentration increases as the thickness of the doping layer decreases. The degradation of the implanted Ge surface can be minimized by performing ion implantation at temperatures that are below −100 °C with ion flux less than 60 nAcm−2 and maximum ion energy less than 120 keV. The implanted layers are flash-lamp annealed for 20 ms in order to inhibit the diffusion of the implanted ions during the recrystallization process.