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A twisted grain boundary is introduced in the tellurium crystal to effectively block phonon propagation while maintaining high electron mobility for superior thermoelectric properties.

We synthesized colloidal cesium metal halide CsMX (M = Fe, Co, Ni; X = Cl, Br) nanoparticles (NPs) and assessed their crystal stability by density functional theory (DFT) calculations. We successfully synthesized Cs

Metal-halide perovskites (MHPs) have attracted tremendous attention as active materials in optoelectronic devices. For light-emitting diode (LED) applications, nanostructuring of MHPs is considered to be inevitable, but its light-enhancement mechanism is still elusive because the particle (or grain) size is often beyond the quantum confinement regime. As motivated by the experimental finding that the nanostructuring can change the preferred crystalline symmetry from the orthorhombic phase to the high-symmetric cubic phase, we here investigated the carrier dynamics in various polymorphic phases of CsPbBr

The excited state quantum dynamics of the organic cation in hybrid perovskites are investigated using the time-dependent density functional theory (TDDFT). The time-dependent non-adiabatic bond fluctuation behaviors reveal that the energy relaxation follows different pathways depending on the chemical bonding characteristics and energy transfer modes within the cation molecule, which can fundamentally affect its photostability. For the ammonium-group-containing cations, such as methylammonium (MA) or ethylammonium (EA), local vibrational modes survive for a long time. However, as their lowest unoccupied molecular orbital (LUMO) having π* characters, the amidinium-group-containing cations, such as formamidinium (FA) or guanidinium (GA), efficiently dissipate deposited energy via chaotic intramolecular vibrational energy redistribution (IVR). The distinct dynamic behaviors of A-site molecular cations are closely related to the quantum ergodicity, which can bring enhanced photochemical stability of FA and GA compared to MA and EA. Our theoretical investigation reveals the quantum chaos origin of better light stability of FA-based perovskites and serves the future research direction of the A-site engineering for better solar cells and light-emitting devices.

Halide perovskite solar cells have been attracting tremendous attention as next-generation solar cell materials because of their excellent optical and electrical properties. Formamidinium lead tri-iodide (FAPbI3) exhibits the narrowest band gap among lead iodide perovskites and shows excellent thermal and chemical stability, also. However, the large-area coating of FAPbI3 needed for commercialization has not been successful because of the instability of the black phase of FAPbI3 at ambient temperature. This study presents a compositional engineering direction to control the polymorph of the FAPbI3 thin film for the shear coating processes, without halide mixing. By adopting a hot substrate above 100 oC, our shear coating process can produce the black phase FA-based halide perovskites without halide mixing. We carefully investigate the Cs-FA and MA-FA mixed lead iodide perovskites’ phase stability by combining the study with thin-film fabrication and ab initio calculations. Cs-FA mixing shows promising behaviors for stabilizing α-FAPbI3 (black phase) compared with MA-FA. Stable FA-rich perovskite films cannot be achieved via shear coating processes with MA-FA mixing. Ab initio calculations revealed that Cs-FA mixing is excellent for inhibiting phase decomposition and water incorporation. This study is the first report that FA-based halide perovskite thin films can be made with the shear coating process without MA-Br mixing. We reveal the origin of the stable film formation with Cs-FA mixing, and present future research directions for fabricating FA-based perovskite thin films using shear coating.

With their dramatic improvement of photoconversion efficiency, metal-halide perovskite (MHP) solar cells are receiving great attention. For successful deployment of these materials as next-generati...

ZnO thin films are of considerable interest because they can be customized by various coating technologies to have high electrical conductivity and high visible light transmittance. Therefore, ZnO thin films can be applied to various optoelectronic device applications such as transparent conducting thin films, solar cells and displays. In this study, ZnO rod and thin films are fabricated using aqueous chemical bath deposition (CBD), which is a low-cost method at low temperatures, and environmentally friendly. To investigate the structural, electrical and optical properties of ZnO for the presence of citrate ion, which can significantly affect crystal form of ZnO, various amounts of the citrate ion are added to the aqueous CBD ZnO reaction bath. As a result, ZnO crystals show a nanorod form without citrate, but a continuous thin film when citrate is above a certain concentration. In addition, as the citrate concentration increases, the electrical conductivity of the ZnO thin films increases, and is almost unchanged above a certain citrate concentration. Cu(In,Ga)Se2 (CIGS) solar cell substrates are used to evaluate whether aqueous CBD ZnO thin films can be applicable to real devices. The performance of aqueous CBD ZnO thin films shows performance similar to that of a sputter-deposited ZnO:Al thin film as top transparent electrodes of CIGS solar cells.

Degradation in CH3NH3PbI3 (MAPbI3), when in contact with commonly used metal oxide transport layer materials in optoelectronic devices, is examined experimentally and theoretically. On the basis of...

The thermal stability and decomposition pathway of formamidinium iodide (FAI, HC(NH2)2I) in contact with NiO and TiO2 are investigated by combined experimental studies and density functional theory (DFT) calculations. Based on the decomposition temperature, we find that the stability decreases as FAI ∼ FAI + TiO2 > FAI + NiO. Moreover, FAPbI3 in contact with NiO and TiO2 shows similar thermal stability behaviour to FAI. The bulk decomposition of FAI occurs via the formation of sym-triazine, and can also produce HCN, and NH4I at ∼280 °C, which further decomposes to NH3 and HI above 300 °C. When FAI comes into contact with NiO, the interfacial reaction triggers decomposition at a much lower temperature (∼200 °C), resulting in the formation of NiI2 as the solid product while releasing NH3 and H2O into the gas phase; sym-triazine and HCN are observed near the FAI bulk decomposition temperature. In contrast, when FAI comes into contact with TiO2, the decomposition temperature is similar to bulk FAI; however, HCN is released at a lower temperature (∼260 °C) compared to sym-triazine. The difference in the degradation behavior of FAI with NiO and TiO2 is elucidated using DFT calculations. Our results show that the interfacial reaction between the organic component of perovskite material and NiO occurs similarly for MA and FA, which thereby can induce device instability.

Structure engineering of trivalent metal halide perovskites (MHPs) such as A3Sb2X9 (A = a monovalent cation such as methyl ammonium (MA), cesium (Cs), and formamidinium (FA) and X = a halogen such as I, Br, and Cl) is of great interest because a two dimensional (2D) layer structure with direct bandgap has narrower bandgap energy than a zero dimensional (0D) dimer structure with indirect bandgap. Here, we demonstrated 2D layer structured FACs2Sb2I6Cl3 MHP by dual-site (A and X site) mixing. Thanks to the lattice-symmetry change by I–Cl mixed halide, the shortest ionic radius of Cs, and the lower solution energy due to dual-site mixing, the FACs2Sb2I6Cl3 MHP had 2D layer structure and thereby the MHP solar cells exhibited improved short-circuit current density.

High-speed continuous deposition of solution-processed perovskite thin films with controlled microstructural morphology has been intensively pursued toward practical commercialization of high-efficiency perovskite solar cells. In order to meet this urgent demand in a timely manner, we present a rapid (~5 mm·s−1) scalable meniscus-controlled coating method to deposit large-grained (>100 μm) perovskite thin films over large area. Shearing movement of the meniscus of perovskite solution, confined by the hydrophobic-treated top and temperature-controlled bottom plates enables a rapid crystallization of perovskite grains, also facilitating the continuous influx of solutes at the meniscus for continuous film growth with less consumption of perovskite solution. Optical and structural analyses revealed that the rapid-shear-deposited perovskite thin films possess a large-grained, densely-packed and highly-crystalline phase. Consequently, perovskite solar cell based this film exhibits the power conversion efficiency of 10.9% even without compositional engineering and additive controls. Therefore, it can be claimed that this rapid shearing deposition of perovskite solution paves a way to achieve a cost-competitive production of the high-efficiency solar cell.

Cr-rich shells are known to decrease the lattice misfit of Y–Ti–O nanoparticles and contribute to high thermal stability. In the present work, the formation of a Cr-rich shell on the Y2Ti2O7/Fe interface is studied via density functional theory and examined with electron microscopy analyses. The density functional theory calculation showed that Cr substitution in Y2Ti2O7 is not allowed. Instead, Cr is favorably segregated on the interface of the Fe site owing to the strong binding energy between Cr and O. Atom probe tomography observations confirmed the formation of a Cr shell at the interface between Y2Ti2O7 nanoparticles and the Fe matrix. Contrary to the density functional theory calculation, a considerable Cr concentration was detected inside the oxide. However, additional transmission electron microscopy observation of very coarse Y2Ti2O7 nanoparticles demonstrated that the Cr concentration is almost negligible inside the oxide, which is consistent with the calculated prediction.

For enhancing the performance and long-term stability of perovskite solar cell (PSC) devices, interfacial engineering between the perovskite and hole-transporting material (HTM) is important. We developed a fluorinated conjugated polymer PFPT3 and used it as an interfacial layer between the perovskite and HTM layers in normal-type PSCs. Interaction of perovskite and PFPT3 via Pb-F bonding effectively induces an interfacial dipole moment, which resulted in energy-level bending; this was favorable for charge transfer and hole extraction at the interface. The PSC device achieved an increased efficiency of 22.00% with an open-circuit voltage of 1.13 V, short-circuit current density of 24.34 mA/cm2, and fill factor of 0.80 from a reverse scan and showed an averaged power conversion efficiency of 21.59%, which was averaged from forward and reverse scans. Furthermore, the device with PFPT3 showed much improved stability under an 85% RH condition because hydrophobic PFPT3 reduced water permeation into the perovskite layer, and more importantly, the enhanced contact adhesion at the PFPT3-mediated perovskite/HTM interface suppressed surface delamination and retarded water intrusion. The fluorinated conjugated polymeric interfacial material is effective for improving not only the efficiency but also the stability of the PSC devices.

Toxicity is the main bottleneck for the commercialization of Pb halide perovskites. Bi has been considered a promising metal cation to replace Pb because of its comparable electronic structures with Pb and better stability. Although experimental and theoretical studies have proposed various Bi-based halides, the present achievements in photovoltaic cells and other photoelectronic device fields do not compete with Pb analogs. Thermodynamic stability, bandgap control, and enhancement of carrier transport are fundamental challenges in the context of intrinsic material properties for developing highly efficient Bi-based devices. This study evaluates the potential of Bi-based halide compounds with good stability and electronic properties through high-throughput density functional theory calculations. Lattice structures and compositions are selected based on previous reports and an open material database. Then, we expanded our dataset to cover all possible compositional variations of A- and X-sites and alloying to B-sites. We examined over six-hundred candidates and found ten new candidates that have not been reported previously. Rb3SbBiI9 exhibits the best-expected efficiency for high-efficiency solar cells among selected compounds, and other compounds can be used as visible-light-generation sources. Analysis of the screening procedure revealed that vacancy-ordered (A3B2X9)-type Bi-halides exhibit significantly favorable characteristics when compared with those of double perovskites and rudorffite-like structures for Bi-based photoelectronic devices.

Silver nanowire (AgNW) electrodes have been employed in solar cells as transparent conducting electrodes (TCEs). When a AgNW electrode is used as a network-type TCE in solar cells, photogenerated charge carriers must laterally travel to reach AgNW networks. If the empty space of the network is larger than the lateral collection length of the charge carriers ( L lc ), a significant fraction of the charge carriers will be lost. Therefore, determination of L lc is essential for choosing and/or designing a suitable network for solar cells. Here, we develop a method to relate the lateral photocurrent measured from a specially designed pattern to the L lc value. We apply this method to Cu(In,Ga)Se2 thin-film solar cells with AgNW TCEs. The L lc value was determined to be ≈ 26 μm in the CdS/CIGS/Mo structure under 1-sun illumination. The measured lateral collection length is much larger than the normal spacing between AgNWs, indicating a high lateral collection efficiency in AgNW TCE-based CIGS thin-film solar cells.

The cesium lead triiodide (CsPbI3) perovskite is a promising candidate for stable light absorbers and red-light-emitting sources due to its outstanding stability. Phase engineering is the most impo...

We demonstrate the ability to fabricate high-quality nanoscale electrical contact between silver nanowires (AgNWs) and underlying semiconducting layers in chalcogenide thin film solar cells. AgNW electrodes have attracted many interests due to their ability for low temperature solution processing. However, they have a drawback that the interfacial defects can be generated between AgNWs and underlying rugged semiconductor layers making it difficult to form high-quality junction. To enhance the junction properties, conducting matrix layers have been adapted. Yet, the issues regarding the AgNW/semiconductor junction have not been fully resolved. We developed a facile method to form robust nanoscale contact between AgNWs and semiconducting thin films to achieve high performance chalcogenide thin film solar cells. The method is to deposit an ultra-thin semiconductor layer on devices using aqueous chemical bath deposition. The chemical bath deposition has capability to effectively fill even nanoscale gap and to form chemically stable bonds as well as an intimate junction. As a proof of concept, a CdS layer (~ 10 nm) was deposited using the chemical bath deposition on Cu(In,Ga)Se2 (CIGS) solar cells with a structure of AgNW/CdS/CIGS/Mo/Glass. We also identified that the key factor governing the current-voltage characteristic is the electrical contact between the AgNW electrode and the CdS buffer layer in CIGS thin film solar cells. The power conversion efficiency of the CIGS cell was dramatically improved from 4.9% to 14.2% owing to high-quality AgNW-CdS electrical contact produced by chemical bath deposition of the additional CdS layer as thin as 10 nm.

Preserving the stability of Sn-based halide perovskites is a primary concern in developing photovoltaic light-absorbing materials for lead-free perovskite solar cells. Whereas the addition of SnX2 (X = F, Cl, Br) has been demonstrated to improve the photovoltaic performance of Sn halide perovskite solar cells, the mechanistic roles of SnX2 in the performance enhancement have not yet been studied appropriately. Here we perform a comparative study of CsSnI3 films and devices and examine how SnX2 additives affect their stability, and the results are corroborated by first-principles-based theoretical calculations. Unlike the conventional belief that the additives annihilate defects, we find that the additives effectively passivate the surface and stabilize the perovskite phase, promoting the stability of CsSnI3. Our mechanism suggests that SnBr2, which shows ca. 100 h of prolonged stability along with a high power conversion efficiency of 4.3%, is the best additive for enhancing the stability of CsSnI3.

Cr is a critical alloying element in Ni-based alloys. The role of Cr on the formation of oxide nuclei in Ni-Cr alloys is theoretically investigated with density functional theory. Our simulation indicates that Cr has strong binding energy with the nearest oxygen and that it enhances the stability of the metal-oxide nucleus. Therefore, oxide dispersion can be promoted by the incorporation of Cr into Ni alloys. Additionally, potential oxide candidates for the oxide strengthening of Ni-Cr alloys are theoretically explored. The findings, through an analysis of electronic structures, suggest that La and Y are most promising when attempting to realize stable oxide formation in Ni-Cr alloys and reveal that the metal used to create the primary oxides should have low electronegativity and a large atomic radius to create stable metal-oxide nuclei.

We quantitatively and analytically investigate the properties of buffer/window junctions and their effects on the energy band alignment and the current-voltage characteristics of Cu(In,Ga)Se2 (CIGS) thin film solar cells with solution processed silver nanowire (AgNW) composite window layers. AgNWs are generally embedded in a moderately conductive matrix layer to ensure lateral collection efficiency of charge carriers photogenerated in the lateral gaps present between AgNWs. Studies on the junctions between a buffer and AgNW-composite window layers and their effects on the performances of CIGS thin film solar cells have seldom been addressed. Here, we show that solution processed AgNW-composite window layers could induce defect states at the buffer/window interface, resulting in poor energy band alignment impeding carrier transport in the solar cells. On the basis of our analysis, we suggest an analytical expression of nmatrixDi2≥3.46×10−5e cm to avoid losses in the power conversion efficiency of the solar cells. nmatrix is the carrier concentration in a matrix layer embedding AgNWs, Di is the negative defect density at the buffer/window interface, and e is the relative dielectric constant of the matrix layer embedding AgNWs.

As a next-generation solar cell, perovskite solar cells (PSCs) have been attracting considerable attention. FAPbI3 is particularly considered as an optimal material with a proper band gap and thus has been employed as a base material for the PSCs with more than 20% efficiency; however, the competitive polymorphic growth of α- and δ-phases is a major hurdle in utilizing this material. To provide the theoretical model of the polymorphic phase competition of FAPbI3 for the first time, we here investigate how compositional engineering can pave a route to control the polymorphic growth of FAPbI3 using density functional theory combined with a statistical-mechanical treatment of the configurational space. We find that dual-site alloying of both cations and halides is critically important to achieve the specific stabilization of the α-phase while maintaining the good miscibility, thermodynamic stability, and optimal band gap property. Based on our first successful theoretical modeling of the FAPbI3 system and it...

Structure engineering of trivalent metal halide perovskites (MHPs) such as A

Quantum confinement-driven band structure engineering of metal halide perovskites (MHPs) is examined for realistically sized structures that consist of up to 105 atoms. The structural and compositional effects on band gap energies are simulated for crystalline CH3NH3PbX3 (X = I/Br/Cl) with a tight-binding approach that has been well-established for electronic structure calculations of multimillion atomic systems. Solid maps of band gap energies achievable with quantum dots, nanowires, and nanoplatelets concerning sizes, shapes, and halide compositions are presented, which should be informative to experimentalists for band gap designs. The pathway to suppress band gap instability that appeared in mixed halide perovskites is proposed, revealing that the red shift induced by halide phase separation can be hugely diminished by reducing sizes and adopting halides of lower electronegativity. Our modeling results on finite MHP structures of over 10 nm dimensions show a blueprint for designs of stable light-emitt...

In this study, green and blue perovskite light-emitting diodes (PeLEDs) were systematically investigated using various organic spacers of different molecular lengths to control the number of dimensions of the PeLED material. The primary perovskite used was CsPbBr 3 , and the organic spacers tested were aniline hydrobromide (AnBr), benzylamine hydrobromide (BABr), phenylethylamine hydrobromide (PEABr), phenylpropylamine hydrobromide (PPABr), and phenylbutylamine hydrobromide (PBABr). By specifically testing different amounts of each spacer, green to blue PeLEDs were prepared and analyzed using XRD and SEM. The best optical and electrical performances were obtained with PEABr as the organic spacer. Using 0.4 mol of PEABr for 1 mol of CsPbBr 3 yielded a green electroluminescence (EL) emission with a CIE of (0.078, 0.745), a maximum current efficiency of 43.9 cd/A, and an EQE of 8.67%, and using 1.6 mol of PEABr per mole of CsPbBr 3 yielded a blue EL emission with a CIE of (0.151, 0.084), a maximum current efficiency of 0.87 cd/A, and an EQE of 0.39%.

Ternary metal halides (A3X2I9) have attracted considerable interest because they have good stability and reduced toxicity compared with Pb-based halide perovskites. The main issue with A3X2I9 is their band gap, which is relatively large for use in a single junction solar cell (1.9–2.2 eV for the Cs3Bi2I9). This theoretical study found that the band gap of Cs3Bi2I9 can be successfully modulated by using dual metal cations, i.e., by forming Cs3BiXI9 (X: trivalent cation). Among the various trivalent atoms investigated, In and Ga showed very promising band gap modulation behaviors. Additionally, the indirect band gap of Cs3Bi2I9 can be changed into a direct band gap.

We report solutions (durable material and degradation prevention method) to minimize the performance degradation of cell components occurring in the solid oxide fuel cell (SOFC) operation. Reliability testing is carried out with the Ni Nd0.1Ce0.9O2-δ (NDC) anode-supported intermediate temperature-SOFCs. For the cathode materials, single perovskite structured Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) and double perovskite structured NdBa0.5Sr0.5Co1.5Fe0.5O5+δ (NBSCF) are prepared and evaluated under harsh SOFC operating conditions. The double perovskite NBSCF cathode shows excellent stability in harsh SOFC environments of high humidity and low flow rate of air. Furthermore, we propose the concurrent fuel and air starvation mode, in which the cell potential is temporarily reduced due to the formation of both fuel-starvation (in the anode) and air-depletion (in the cathode) concurrently under a constant load. This is carried out in order to minimize the performance decay of the stable NBSCF-cell through the periodic and extra reduction of a H 2 O (and a O 2 ) in the anode. The operating-induced degradation of SOFCs, which are ordinarily assumed to be unrecoverable, can be completely circumvented by the proposed periodical operation logic to prevent performance degradation (concurrent fuel-starvation and air-depletion mode).

While oxide dispersion strengthening of Fe-based alloys has been actively studied, the theoretical investigation of dispersion strengthening in Ni-based alloys is still lacking. This study presents potential oxide candidates for oxide dispersion strengthened Ni-based alloys using density functional calculations. By comparing the formation and binding energies of various metal oxides and lanthanide oxides, we determined that the lanthanide oxides can be efficient oxide dispersion sources and have the potential to compete with yttrium oxides for Ni alloys. We also found that the vacancies in a Ni–lanthanide oxide system play an important role in stabilizing nuclei formation process.

Recently Organic-inorganic halide perovskite (OIHP) solar cells have become one of the most promising next-generation photovoltaic materials due to their excellent electrical and optical properties. Formamidinium lead triiodide (HC(NH2)2PbI3, FAPbI3) exhibits the narrowest band gap (~1.45 eV) among Pb-based halide perovskites, which is closer to Shockley-Queisser limit than that (~1.55 eV) of Methylammonium Lead Iodide (CH3NH3PbI3, MAPbI3). Therefore, FAPbI3 has been widely adopted for recently developed highly efficient photovoltaic cells. In addition, FAPbI3 has better stability than MAPbI3, which can be easily decomposed at a high temperature or humid environment. The spin-coating has been widely adopted to make FAPbI3-based solar cells, whereas the large-area coating technologies have not been extensively studied, yet. This study presents the compositional engineering research on the polymorph control of formamidinium-based lead halide perovskites for the large-area film coating. The polymorph control of FAPbI3 has been one of the most important issues since its first appearance in photovoltaic applications. Non-perovskite structure (δ-FAPbI3) is thermodynamically more stable than the three-dimensional perovskite structure (α-FAPbI3). We adopted the shear coating method to make perovskite layers and controlled the polymorphism through A-site mixing. MA, commonly used A-site molecule, is excluded because MA can be a weak spot at the humid condition. Br mixing is not applied due to the photo-induced phase separation issue. Our results reveal that double-cation mixing (Cs-FA or Rb-FA) is not enough and triple-cation mixing (Rb-Cs-FA) cannot be avoided to make robust α-FAPbI3 for the shear coating process. We present the ternary phase diagram of (Rb-CS-FA)PbI3 to show the process window based on the XRD analysis of mixed perovskite films. The photovoltaic cell shows 15.8% power conversion efficiency (PCE) at the best compositional mixing point, which is the best PCE for FA-based perovskite solar cells fabricated by shear coating method without MA-Br mixing.

Preserving the stability of Sn-based halide perovskites is a primary concern in developing photovoltaic light-absorbing materials for lead-free perovskite solar cells. Whereas the addition of SnX

We examine the effect of the structural confinement on optical properties of organic lead halide perovskite supercells of various shapes. With a set of 8-band tight-binding parameters that reproduce the bulk band gaps and offsets of MAPb (I/ Br/Cl) 3 that have been known through DFT simulations, we explore the band gap of finite supercells that have homogeneous and mixed halides. This preliminary work already delivers a set of information that is useful for potential device designs because band gaps of organic lead halide perovskite supercells are rarely understood, particularly for realistically sized finite structures.

Organic–inorganic perovskites are promising materials for improving the efficiency of solar cells, but there are still uncovered issues on the understanding of their electronic band structures. Using first-principles calculations, we investigate the electronic band features of organo-lead iodide perovskites and present the efficient model to predict the band gap variation based on the orbital interaction scheme. The orbital interaction between Pb and I atoms can be controlled through the structural modification such as the change in lattice constant and the deviation of I atoms from cubic symmetry sites. The increase of the lattice constant and the positional distortion of I atoms from the cubic symmetry sites lead to the increase of the band gap. With our findings, puzzling band gap variation behaviors in previous experiments and simulations can be understood, and we suggest a pathway to precisely control their band gap. Our study can serve as the design rule for band gap engineering for various kinds of...

The dependency of dopant-distributions on channel diameters in realistically sized, highly phosphorus-doped silicon nanowires is investigated with an atomistic tight-binding approach coupled to self-consistent Schrödinger-Poisson simulations. By overcoming the limit in channel sizes and doping densities of previous studies, this work examines electronic structures and electrostatics of free-standing circular silicon nanowires that are phosphorus-doped with a high density of ∼ 2 × 10(19) cm(-3) and have 12 nm-28 nm cross-sections. Results of analysis on the channel energy indicate that the uniformly distributed dopant profile would be hardly obtained when the nanowire cross-section is smaller than 20 nm. Insufficient room to screen donor ions and shallower impurity bands are the primary reasons of the nonuniform dopant-distributions in smaller nanowires. Being firmly connected to the recent experimental study (Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 15254-15258), this work establishes the first theoretical framework for understanding dopant-distributions in over-10 nm highly doped silicon nanowires.