Photoluminescence and Electroluminescence from Tris(8‐ hydroxyquinoline)aluminum Nanowires Prepared by Adsorbent‐Assisted Physical Vapor Deposition

Single‐crystalline nanowires are successfully prepared from a small organic functional molecule, tris(8‐hydroxyquinoline)aluminum (Alq₃), by an adsorbent‐assisted physical‐vapor‐deposition method. The introduction of adsorbents can decrease the sublimation temperature of Alq₃, and slow the weight‐loss process markedly, which is proven to be indispensable in improving the uniformity of the as‐prepared Alq₃ nanowires. Measurements of the optical properties reveal that the absorption spectra of the Alq₃ nanowires show an obvious blue‐shift with decreasing diameter. The photoluminescence vibrational fine structure emerges and becomes pronounced with increasing excitation energy, which is attributed to the ordered orientation of the Alq₃ molecules in the nanowires. Furthermore, the Alq₃ nanowires are fabricated into an electroluminescent device, which has an obvious size‐dependent performance.     

Growth of Heteroepitaxial ZnO Thin Films on GaN‐Buffered Al2O3 (0001) Substrates by Low‐Temperature Hydrothermal Synthesis at 90 °C

Heteroepitaxial ZnO films are successfully grown on nondoped GaN‐buffered Al₂O₃ (0001) substrates in water at 90 °C using a two‐step process. In the first step, a discontinuous ZnO thin film (ca. 200 nm in thickness) consisting of hexagonal ZnO crystallites is grown in a solution containing Zn(NO₃)·6 H₂O and NH₄NO₃ at ca. pH 7.5 for 24 h. In the second step, a dense and continuous ZnO film (ca. 2.5 μm) is grown on the first ZnO thin film in a solution containing Zn(NO₃)·6 H₂O and sodium citrate at ca. pH 10.9 for 8 h. Scanning electron microscopy, X‐ray diffraction, UV‐vis absorption spectroscopy, photoluminescence spectroscopy, and Hall‐effect measurement are used to investigate the structural, optical, and electrical properties of the ZnO films. X‐ray diffraction analysis shows that ZnO is a monocrystalline wurtzite structure with an epitaxial orientation relationship of (0001)[11 0]_ZnO∥(0001)[11 0]_GaN. Optical transmission spectroscopy of the two‐step grown ZnO film shows a bandgap energy of 3.26 eV at room temperature. A room‐temperature photoluminescence spectrum of the ZnO film reveals only a main peak at ca. 380 nm without any significant defect‐related deep‐level emissions. The electrical property of ZnO film showed n‐type behavior with a carrier concentration of 3.5 × 10¹⁸ cm^–3 and a mobility of 10.3 cm² V^–1 s^–1.     

An Alternative Copolymer of Carbazole and Thieno[3,4b]‐Pyrazine: Synthesis and Mercury Detection

A donor‐π‐acceptor (D‐π‐A) alternative copolymer of carbazole and thieno[3,4b]‐pyrazine [P(CZ‐TPZ)] is synthesized through a Wittig–Horner reaction. In dilute THF solution, the absorption spectrum of P(CZ‐TPZ) shows two absorption peaks at 306 and 452 nm, respectively, and the PL spectrum of the polymer solution displays a PL peak maximum at 543 nm. The polymer possesses relatively high sensitivity and selectivity for Hg²⁺ detection. Upon addition of Hg²⁺ into its THF solution (containing 0.3% CH₃CN), P(CZ‐TPZ) exhibits a new absorption peak at 560～600 nm and its emission was quenched dramatically. The Hg²⁺ detection shows high selectivity in comparison with the other cations of Na⁺, K⁺, Mg²⁺, Ba²⁺, Al³⁺, Cu²⁺, Cd²⁺, Pb²⁺, Ni²⁺, Mn²⁺, and Co²⁺. The Hg²⁺ detection limit of the polymer solution by emission quenching is found to be 1 × 10^?7 mol L^?1. P(CZ‐TPZ) also shows a selective chromogenic behavior toward Hg²⁺ with color change of the solution from yellow to blue dark which can be detected with the naked eye, the detection limit reaches 1 × 10^?6 mol L^?1 with a 1 × 10^?4 mol L^?1 polymer solution. The absorption and PL spectral change can be resumed after adding thiourea, therefore the sensing ability of the polymer is re‐usable with the treatment of thiourea. The results indicate that P(CZ‐TPZ) is a promising chemosensor for the Hg²⁺ detection.     

The Relation Between Open‐Circuit Voltage and the Onset of Photocurrent Generation by Charge‐Transfer Absorption in Polymer : Fullerene Bulk Heterojunction Solar Cells

Photocurrent generation by charge‐transfer (CT) absorption is detected in a range of conjugated polymer–[6,6]‐phenyl C₆₁ butyric acid methyl ester (PCBM) based solar cells. The low intensity CT absorption bands are observed using a highly sensitive measurement of the external quantum efficiency (EQE) spectrum by means of Fourier‐transform photocurrent spectroscopy (FTPS). The presence of these CT bands implies the formation of weak ground‐state charge‐transfer complexes in the studied polymer–fullerene blends. The effective band gap (E_g) of the material blends used in these photovoltaic devices is determined from the energetic onset of the photocurrent generated by CT absorption. It is shown that for all devices, under various preparation conditions, the open‐circuit voltage (V_oc) scales linearly with E_g. The redshift of the CT band upon thermal annealing of regioregular poly(3‐hexylthiophene):PCBM and thermal aging of poly(phenylenevinylene)(PPV):PCBM photovoltaic devices correlates with the observed drop in open‐circuit voltage of high‐temperature treated versus untreated devices. Increasing the weight fraction of PCBM also results in a redshift of E_g, proportional with the observed changes in V_oc for different PPV:PCBM ratios. As E_g corresponds with the effective bandgap of the material blends, a measurement of the EQE spectrum by FTPS allows us to measure this energy directly on photovoltaic devices, and makes it a valuable technique in the study of organic bulk heterojunction solar cells.     

A New Strategy to Effectively Suppress the Initial Capacity Fading of Iron Oxides by Reacting with LiBH4

In this work, a new facile and scalable strategy to effectively suppress the initial capacity fading of iron oxides is demonstrated by reacting with lithium borohydride (LiBH₄) to form a B‐containing nanocomposite. Multielement, multiphase B‐containing iron oxide nanocomposites are successfully prepared by ball‐milling Fe₂O₃ with LiBH₄, followed by a thermochemical reaction at 25–350 °C. The resulting products exhibit a remarkably superior electrochemical performance as anode materials for Li‐ion batteries (LIBs), including a high reversible capacity, good rate capability, and long cycling durability. When cycling is conducted at 100 mA g^?1, the sample prepared from Fe₂O₃–0.2LiBH₄ delivers an initial discharge capacity of 1387 mAh g^?1. After 200 cycles, the reversible capacity remains at 1148 mAh g^?1, which is significantly higher than that of pristine Fe₂O₃ (525 mAh g^?1) and Fe₃O₄ (552 mAh g^?1). At 2000 mA g^?1, a reversible capacity as high as 660 mAh g^?1 is obtained for the B‐containing nanocomposite. The remarkably improved electrochemical lithium storage performance can mainly be attributed to the enhanced surface reactivity, increased Li⁺ ion diffusivity, stabilized solid‐electrolyte interphase (SEI) film, and depressed particle pulverization and fracture, as measured by a series of compositional, structural, and electrochemical techniques.     

Optical and EPR Spectroscopic Studies of Deep Red Light Emitting Fe-Doped LiAl<Subscript>5</Subscript>O<Subscript>8</Subscript> Phosphor Prepared Via Propellant Combustion Route

LiAl₅O₈ doped with Fe was synthesized by a propellant combustion route at furnace temperature of 773 K. The phosphor was characterized using powder x-ray diffraction, optical absorption, electron paramagnetic resonance (EPR) and photoluminescence spectroscopic techniques. The optical absorption spectrum exhibits a broad band at 242 nm characteristic of charge transfer between Fe³⁺–O^2?. On excitation with 293 nm, emission band for the Fe³⁺ ion was observed at 687 nm. The CIE (International Commission on Illumination or Commission Internationale de l’Elcairage) coordinates for the system were evaluated adopting standard procedure which suggested that the system can be effective as a deep red emitting phosphor. The EPR spectrum of this phosphor exhibits a number of resonance signals characteristic of Fe³⁺ ions. The resonance signals at g = 3.16, 2.27 are attributed to Fe³⁺ present at tetrahedral site with an axial symmetry. The resonance signals at g = 1.98 and 1.43 are attributed to Fe³⁺ ions in octahedral site with an axial symmetry. Various EPR parameters such as the number of spins, Gibbs free energy, magnetic susceptibility, Curie constant and effective magnetic moment values are calculated and compared at room temperature and 110 K.     

Enhancement of dye sensitized solar cell efficiency via incorporation of upconverting phosphor nanoparticles as spectral converters

Upconverting NaYF₄:Yb³⁺,Er³⁺/NaYF₄ core‐shell (CS) nanoparticles (NPs) were synthesized by thermal decomposition of lanthanide trifluoroacetate precursors and mixed with TiO₂ NPs to fabricate dye‐sensitized solar cells (DSSCs). The CS geometry effectively prevents the capture of electrons because of the surface states and improves photo‐emission. The as‐synthesized CS NPs show upconversion (UC) luminescence, converting near infrared (NIR) light into visible light (450–700 nm), making the photon absorption by the ruthenium‐based dyes (which have little or no absorption in the NIR region) possible. The champion DSSCs fabricated using CS UC NPs (average size = 25 nm) show enhancements of ~12.5% (sensitized with black/N749 dye) and of ~5.5% (sensitized with N719 dye) in overall power conversion efficiency under AM 1.5G illumination. This variation in the enhancement of the DSSC efficiencies for black and N719 dyes is attributed to the difference in the extinction coefficient and the absorption wavelength range of dyes. Incident photon‐to‐current conversion efficiency measurements also evidently showed the photocurrent enhancement in the NIR region of the spectrum because of the UC effect. The results prove that the augmentation in efficiency is primarily due to NIR to visible spectrum modification by the fluorescent UC NPs. Copyright © 2015 John Wiley & Sons, Ltd.     

Design of Multilayered Nanostructures and Donor–Acceptor Interfaces in Solution‐Processed Thin‐Film Organic Solar Cells

Multilayered polymer thin‐film solar cells have been fabricated by wet processes such as spin‐coating and layer‐by‐layer deposition. Hole‐ and electron‐transporting layers were prepared by spin‐coating with poly(3,4‐ethylenedioxythiophene) oxidized with poly(4‐styrenesulfonate) (PEDOT:PSS) and fullerene (C₆₀), respectively. The light‐harvesting layer of poly‐(p‐phenylenevinylene) (PPV) was fabricated by layer‐by‐layer deposition of the PPV precursor cation and poly(sodium 4‐styrenesulfonate) (PSS). The layer‐by‐layer technique enables us to control the layer thickness with nanometer precision and select the interfacial material at the donor–acceptor heterojunction. Optimizing the layered nanostructures, we obtained the best‐performance device with a triple‐layered structure of PEDOT:PSS|PPV|C₆₀, where the thickness of the PPV layer was 11 nm, comparable to the diffusion length of the PPV singlet exciton. The external quantum efficiency spectrum was maximum (ca. 20%) around the absorption peak of PPV and the internal quantum efficiency was estimated to be as high as ca. 50% from a saturated photocurrent at a reverse bias of ?3 V. The power conversion efficiency of the triple‐layer solar cell was 0.26% under AM1.5G simulated solar illumination with 100 mW cm^?2 in air.     

Molecular Design of Mesoporous NiCo2O4 and NiCo2S4 with Sub‐Micrometer‐Polyhedron Architectures for Efficient Pseudocapacitive Energy Storage

Spinel‐type NiCo₂O₄ (NCO) and NiCo₂S₄ (NCS) polyhedron architectures with sizes of 500–600 nm and rich mesopores with diameters of 1–2 nm are prepared facilely by the molecular design of Ni and Co into polyhedron‐shaped zeolitic imidazolate frameworks as solid precursors. Both as‐prepared NCO and NCS nanostructures exhibit excellent pseudocapacitance and stability as electrodes in supercapacitors. In particular, the exchange of O^2? in the lattice of NCO with S^2? obviously improves the electrochemical performance. NCS shows a highly attractive capacitance of 1296 F g^?1 at a current density of 1 A g^?1, ultrahigh rate capability with 93.2% capacitance retention at 10 A g^?1, and excellent cycling stability with a capacitance retention of 94.5% after cycling at 1 A g^?1 for 6000 times. The asymmetric supercapacitor with an NCS negative electrode and an active carbon positive electrode delivers a very attractive energy density of 44.8 Wh kg^?1 at power density 794.5 W kg^?1, and a favorable energy density of 37.7 Wh kg^?1 is still achieved at a high power density of 7981.1 W kg^?1. The specific mesoporous polyhedron architecture contributes significantly to the outstanding electrochemical performances of both NCO and NCS for capacitive energy storage.     

Synthesis and Characterization of Crystalline Ag2Se Nanowires Through a Template‐Engaged Reaction at Room Temperature

Single‐crystalline Ag₂Se nanowires have been successfully synthesized through a template‐engaged topotactic reaction in which nanowires of trigonal selenium were transformed into Ag₂Se by reacting with aqueous AgNO₃ solutions at room temperature (RT). An interesting size‐dependent transition between two crystal structures has also been observed for this newly synthesized one‐dimensional system: The Ag₂Se nanowires adopted a tetragonal structure when their diameters were less than ∼40 nm; an orthorhombic structure was found to be more favorable as the diameter of these nanowires was increased beyond 40 nm. Since this reaction can be carried out at ambient pressure and temperature, it should be straightforward to scale up the entire process for the high‐volume production of Ag₂Se nanowires with well‐controlled sizes and crystal structures. These highly uniform nanowires of single‐crystalline Ag₂Se are potentially useful as photosensitizers, superionic conductors, magnetoresistive compounds, or thermoelectric materials. This work also represents the first demonstration of a template‐engaged process capable of generating single‐crystalline nanowires from the solution‐phase and at RT.     

Extremely Low Operating Voltage Green Phosphorescent Organic Light‐Emitting Devices

Organic light‐emitting devices (OLEDs) are expected to be adopted as the next generation of general lighting because they are more efficient than fluorescent tubes and are mercury‐free. The theoretical limit of operating voltage is generally believed to be equal to the energy gap, which corresponds to the energy difference between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) for the emitter molecule divided by the electron charge (e). Here, green OLEDs operating below a theoretical limit of the energy gap (E_g) voltage with high external quantum efficiency over 20% are demonstrated using fac‐tris(2‐phenylpyridine)iridium(III) with a peak emission wavelength of 523 nm, which is equivalent to a photon energy of 2.38 eV. An optimized OLED operates clearly below the theoretical limit of the E_g voltage at 2.38 V showing 100 cd m^?2 at 2.25 V and 5000 cd m^?2 at 2.95 V without any light outcoupling enhancement techniques.     

Layered H2Ti6O13‐Nanowires: A New Promising Pseudocapacitive Material in Non‐Aqueous Electrolyte

Layered H₂Ti₆O₁₃‐nanowires are prepared using a facile hydrothermal method and their Li‐storage behavior is investigated in non‐aqueous electrolyte. The achieved results demonstrate the pseudocapacitive characteristic of Li‐storage in the layered H₂Ti₆O₁₃‐nanowires, which is because of the typical nanosize and expanded interlayer space. The as‐prepared H₂Ti₆O₁₃‐nanowires have a high capacitance of 828 F g^?1 within the potential window from 2.0 to 1.0 V (vs. Li/Li⁺). An asymmetric supercapacitor with high energy density is developed successfully using H₂Ti₆O₁₃‐nanowires as a negative electrode and ordered mesoporous carbon (CMK‐3) as a positive electrode in organic electrolyte. The asymmetric supercapacitor can be cycled reversibly in the voltage range of 1 to 3.5 V and exhibits maximum energy density of 90 Wh kg^?1, which is calculated based on the mass of electrode active materials. This achieved energy density is much higher than previous reports. Additionally, H₂Ti₆O₁₃//CMK‐3 asymmetric supercapacitor displays the highest average power density of 11 000 W kg^?1. These results indicate that the H₂Ti₆O₁₃//CMK‐3 asymmetric supercapacitor should be a promising device for fast energy storage.     

Tetraphenylimidazole‐Based Excited‐State Intramolecular Proton‐Transfer Molecules for Highly Efficient Blue Electroluminescence

Aiming for highly efficient blue electroluminescence, we have designed and synthesized a novel class of tetraphenylimidazole‐ based excited‐state intramolecular proton‐transfer (ESIPT) molecules with covalently linked charge‐transporting functional groups (carbazole‐ and oxadiazole‐functionalized hydroxyl‐substituted tetraphenylimidazole (HPI), i.e., HPI‐Cbz and HPI‐Oxd, respectively). High T_g (ca. 130 °C) amorphous films of HPI‐Cbz and HPI‐Oxd showed intense and ideal blue‐light emission (λ_max = 462 and 468 nm, Φ_PL = 0.44 and 0.38) with a large Stokes shift of over 160 nm and a narrow full width at half‐maximum of less than 65 nm. Organic light‐emitting devices using HPI‐Cbz and HPI‐Oxd as the emitting layer generated an efficient blue electroluminescence (EL) emission peaking at around 460 nm with excellent CIE coordinates of (x, y) = (0.15, 0.11). A maximum external quantum efficiency of 2.94%, and a maximum brightness of 1 229 cd m⁻² at 100 mA cm⁻², as well as a low turn‐on voltage of 4.8 V were achieved in this work.     

Highly Porous and Preferentially Oriented {100} Platinum Nanowires and Thin Films

Highly {100} oriented Pt deposits were prepared by electrodeposition from a 10 mM HCl, 100 mM KCl and Na₂PtCl₆.xH₂O electrolyte. The deposits were prepared in the form of thin films and array of nanowires. A qualitative assessment of the proportion of {100} oriented Pt surfaces was obtained through X‐ray diffraction measurements and cyclic voltammetry in 0.5 M H₂SO₄. The effect of the deposition potential, E_dep, temperature of the electrolyte, T_dep, platinum salt concentration [Na₂PtCl₆.xH₂O], and nature of the substrate were investigated. It was shown that the proportion of {100} oriented Pt surfaces reaches a maximum for E_dep = ‐0.35 V vs SCE. Moreover, this proportion increases steadily as T_dep and [Na₂PtCl₆.xH₂O] are decreased from 75 to 25 °C and from 2.5 to 0.25 mM, respectively. Scanning electron microscopy and high‐resolution transmission electron microscopy micrographs indicate that the more oriented samples are made of pine tree‐like structures that are effectively single crystals, and that the growth facets appear to be close to the {001} plane. This observation also clearly indicates that the plane exposed during the CV experiment is also {001}. As suggested by these micrographs, the films and nanowires are highly porous and roughness factors as large as 1000 were obtained on highly {100} oriented Pt nanowires. The predominance of {100} facets is attributed to their energetically favoured growth in the presence of hydrogen, and is shown to be significantly enhanced when the mass transport of Pt⁴⁺ is limited. Due to the predominance of {100} facets, the normalized electrocatalytic activity (μA cm^?2_Pt) for the electro‐oxidation of hydrazine and ammonia is higher than non‐oriented polycrystalline Pt by a factor of 4 and 2.7, respectively.     

Porous Si Nanowires from Cheap Metallurgical Silicon Stabilized by a Surface Oxide Layer for Lithium Ion Batteries

In the quest to develop next generation lithium ion battery anode materials, satisfactory electrochemical performance and low material/fabrication cost are the most desirable features. In this article, porous Si nanowires are synthesized by a cost‐effective metal‐assisted chemical etching method using cheap metallurgical silicon as feedstock. More importantly, a thin oxide layer (≈3 nm) formed on the surface of porous Si nanowires stabilizes the cycling performance of lithium ion batteries. Such an oxide coating is able to constrain the huge volume expansion of the underlying Si, yet it is thin enough to ensure good permeability for both lithium ions and electrons. Therefore, the extraordinary storage capacity of Si can be well retained in prolonged electrochemical cycles. Specifically, Si/SiO_x nanowires deliver a reversible capacity of 1503 mAh g^?1 at the 560th cycle at a current density of 600 mA g^?1, demonstrating an average of only 0.04% drop per cycle compared with its initial capacity. Furthermore, the highly porous structure and thin Si wall facilitate the electrolyte penetration and shorten the solid‐state lithium transportation path, respectively. As a result, stable and satisfactory reversible capacities of 1297, 976, 761, 548, and 282 mAh g^?1 are delivered at current densities of 1200, 2400, 3600, 4800, and 7200 mA g^?1, respectively.     

Influence of heat treatment on the structural,optical and electrical properties of Cd20Sn10Se70 thin films

The effect of annealing temperature (T_a) on the structural, optical, and electrical properties of thermally evaporated Cd₂₀Sn₁₀Se₇₀ thin films has been investigated. Differential Thermal Analysis (DTA) was used to determine the glass transition temperature (T_g) of the prepared alloy. X-ray diffraction studies showed that the as-deposited film and the films that were annealed at T_a<T_g are of low crystallinity. On annealing above T_g, these films showed a polycrystalline nature. The surface morphology and microstructure of as-deposited and annealed films have been examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Their optical constants were calculated from the transmittance measurements in the range 200–2500 nm. The dispersion of refractive index was analyzed in terms of the single-oscillator Wemple-Di Domenico model. Analysis of the optical absorption data indicates that the optical band gap E_g of these films obeys Tauc׳s relation for the allowed direct transition. The optical band gap E_g as well as the activation energy for the electrical conduction ∆E were found to increase with increase of annealing temperature up to T_g, whereas above T_g there is a remarkable decrease in both E_g and ∆E. The obtained results were interpreted in terms of the Mott-Davis model and amorphous–crystalline transformation.     

Nanostructured Li2MnSiO4/C Cathodes with Hierarchical Macro‐/Mesoporosity for Lithium‐Ion Batteries

Li₂MnSiO₄/C nanocomposite with hierarchical macroporosity is prepared with poly(methyl methacrylate) (PMMA) colloidal crystals as a sacrificial hard‐template and water‐soluble phenol‐formaldehyde (PF) resin as the carbon source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses confirm that the periodic macropores are ≈400 nm in diameter with 20–40 nm walls comprising Li₂MnSiO₄/C nanocrystals that produce additional large mesopores (< 30 nm) between the nanocrystals. The nanostructured Li₂MnSiO₄/C cathode exhibits a high reversible discharge capacity of 200 mAh g^?1 at C/10 (16 mA g^?1) rate at 1.5–4.8 V at 45 °C. Although the discharge capacity can be further increased on operating at 55 °C, the sample exhibits a relatively fast capacity fade at 55 °C, which can be partially solved by simply narrowing the voltage window to avoid side reactions of the electrolyte. The good performance of the Li₂MnSiO₄/C cathodes is attributed to the unique macro‐/mesostructure of the silicate coupled with uniform carbon coating.     

Electron Paramagnetic Resonance and Photoluminescence Studies of LaMgAl11O19:Mn2+ Green Phosphors

Manganese-doped LaMgAl₁₁O₁₉ powder has been prepared by an easy combustion method. Powder x-ray diffraction and scanning electron microscopy have been used to characterize the as-prepared phosphor. The electron paramagnetic resonance (EPR) spectrum of LaMgAl₁₁O₁₉:Mn²⁺ phosphor exhibits six-line hyperfine structure centered at g ≈ 1.973. The number of spins participating in resonance (N) and the paramagnetic susceptibility (χ) for the resonance signal at g ≈ 1.973 have been calculated as a function of temperature. The photoluminescence spectrum exhibits green emission at 516 nm, which is attributed to ⁴T₁ → ⁶A₁ transition of Mn²⁺ ions. From EPR and luminescence studies, it is observed that Mn²⁺ ions occupy Mg²⁺ sites and Mn²⁺ ions are located at tetrahedral sites in the prepared phosphors.     

Near‐Infrared Small Molecule Acceptor Enabled High‐Performance Nonfullerene Polymer Solar Cells with Over 13% Efficiency

One of the most promising approaches to achieve high‐performance polymer solar cells (PSCs) is to develop nonfullerene small molecule acceptors (SMAs) with an absorption extending to the near‐infrared (NIR) region. In this work, two novel SMAs, namely, BTTIC and BTOIC, are designed and synthesized, with optical bandgaps (E_g^opt) of 1.47 and 1.39 eV, respectively. Desipte the narrow E_g^opt, the PBDB‐T:BTTIC‐ and PBDB‐T:BTOIC‐based PSCs can maintain high V_OCs of over 0.90 and 0.86 V, respectively, with low energy losses (E_loss) < 0.6 eV. Meanwhile, due to the favorable morphology of the PBDB‐T:BTTIC blend, balanced carrier mobilities are achieved. The high external quantum efficiencies enable a high power conversion efficiency (PCE) up to 13.18% for the PBDB‐T:BTTIC‐based PSCs. In comparison, BTOIC shows an excessive crystallization propensity owing to its oxyalkyl side groups, which eventually leads to a relatively low PCE for the PBDB‐T:BTOIC‐based PSCs. Overall, this work provides insights into the design of novel NIR‐absorbing SMAs for nonfullerene PSCs.     

A Highly Stable,New Electrochromic Polymer: Poly(1,4‐bis(2‐(3′,4′‐ethylenedioxy) thienyl)‐2‐methoxy‐5‐2″‐ethylhexyloxybenzene)

A highly stable new electrochromic polymer, poly(1,4‐bis(2‐(3′,4′‐ethylenedioxy)thienyl)‐2‐methoxy‐5‐2″‐ethylhexyloxybenzene) (P(BEDOT‐MEHB)) was synthesized and its electrochemical and electrochromic properties are reported. P(BEDOT‐MEHB) showed a very well defined electrochemistry with a relatively low oxidation potential of the monomer at + 0.44 V versus Ag/Ag⁺, E_1/2 at – 0.35 V versus Ag/Ag⁺ and stability to long‐term switching up to 5000 cycles. A high level of stability to over‐oxidation has also been observed as this material shows limited degradation of its electroactivity at potentials 1.4 V above its half‐wave potential. Spectroelectrochemistry showed that the absorbance of the π–π* transition in the neutral state is blue‐shifted compared to PEDOT, displaying a maximum at 538 nm (onset at 640 nm), thus giving an almost colorless, highly transparent oxidized polymer with a bandgap of 1.95 eV. Different colors observed at different oxidation levels and strong absorption in the near‐IR make this polymer a good candidate for several applications.