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Starting from the Hellmann-Feynman theorem, an expression is derived for the interaction energy in forming a noncovalently found complex. It invokes only classical electrostatics, involving the charge distributions of the components as they are in the complex. We propose a method for obtaining these from the total charge distribution. Integration over the electronic densities is carried out by a numerical procedure slightly modified from that of Gavezzotti. We calculate the interaction energies for thur molecular dimers at a variety of computational levels. The results are analyzed and compared to the best estimated values available in the literature. [ABSTRACT FROM AUTHOR]

Limited stability of blue quantum dot light-emitting diodes (QLEDs) under current stress impedes commercialization. Multi-layer structures of the state-of-the-art blue QLEDs pose significant difficulty in the fundamental understanding of degradation mechanisms. Here, by applying transient electroluminescence measurements, we disentangle charge transport in both pristine and degraded blue QLEDs. By varying thicknesses of the charge transport layers and the emissive layer, respectively, we show that the charge transport in pristine QLEDs is primarily dominated by holes. Furthermore, the degradation of QLEDs under electrical stress is governed by the decrease of hole transport in the emissive quantum dot layer due to the formation of hole traps. [ABSTRACT FROM AUTHOR]

Abstract: We present here the effect of counter anion size in tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) complexes [Ru(dpp)3X2] (X=Cl−, BF4 −, ClO4 −, PF6 − and AsF6 −) on their doped electrophosphorescent device properties. The performance of organic light-emitting diodes (OLEDs) based on these complexes is influenced by the counter anions, that is the efficiency enhances by increasing the counter anion size from small Cl− to large AsF6 −. Among the five complexes, [Ru(dpp)3(AsF6)2] shows the best single layer diode performance with the luminous efficiency of 4.25cdA−1. The possible reasons are carefully studied on the complex properties and their luminescence processes in light-emitting layers. It is found that the size of counter anion affects properties of complex in many aspects such as solubility and photophysical properties. The result shows that the differences in luminescence quantum yields of complexes, the energy-transfer abilities, as well as the charge injection, transfer and trapping abilities of devices related to the counter anions are the major factors in the different performance of doped OLEDs. [Copyright &y& Elsevier]

Abstract: Selectivity for gas separation from a binary mixture in metal organic framework (MOF) materials is identified as arising from a window effect. Our initial analysis based on geometrical models shows that the selectivity, which is related to shape and size of the gas molecules, can be tuned by the window size. Classical molecular dynamics are then used to evaluate CO2/N2 selectivities in MOF-5 derivatives with various window structures. The results verify that the size/shape of molecular windows can change diffusion rates and consequently result in selectivity enhancement. The effect may effectively boost the overall performance of diffusion-driven separation in MOFs. [Copyright &y& Elsevier]

Molecular modeling methods are used to estimate the influenceofimpurity species: water, O2, and SO2in fluegas mixtures present in postcombustion CO2capture usinga metal organic framework, HKUST-1, as a model sorbent material. Coordinatedand uncoordinated water effects on CO2capture are analyzed.Increase of CO2adsorption is observed for both cases,which can be attributed to the enhanced binding energy between CO2and HKUST-1 due to the introduction of a small amount ofwater. Density functional theory calculations indicate that the bindingenergy between CO2and HKUST-1 with coordinated water is∼1 kcal/mol higher than that without coordinated water. Itis found that the improvement of CO2/N2selectivityinduced by coordinated water may mainly be attributed to the increasedCO2adsorption on the hydrated HKUST-1. On the other hand,the enhanced selectivity induced by uncoordinated water in the fluegas mixture can be explained on the basis of the competitionof adsorption sitesbetween water and CO2(N2). At low pressures, a significant CO2/N2selectivity increase is due to the increase of CO2adsorptionand decrease of N2adsorption as a consequence of competitionof adsorption sites between water and N2. However, withmore water molecules adsorbed at higher pressures, the competitionbetween water and CO2leads to the decrease of CO2adsorption capacity. Therefore, high pressure operation shouldbe avoided in HKUST-1 sorbents for CO2capture. In addition,the effects of O2and SO2on CO2capturein HKUST-1 are investigated: The CO2/N2selectivitydoes not change much even with relatively high concentrations of O2in the flue gas (up to 8%). A slightly lower CO2/N2selectivity of a CO2/N2/H2O/SO2mixture is observed compared with that ina CO2/N2/H2O mixture, especiallyat high pressures, due to the strong SO2binding with HKUST-1. [ABSTRACT FROM AUTHOR]

A computational study using density functional theoryis carriedout to investigate the reaction mechanism of ethanol steam reformingon Co(0001) surfaces. The adsorption properties of the reactant, possibleintermediates, and products are carefully examined. The reaction pathwayand related transition states are also analyzed. According to ourcalculations, the reforming mechanism primarily consisting of dehydrogenationsteps of ethanol, ethoxy, methanol, methoxy, and formic acid, is feasibleon Co(0001) surfaces. It is also found that the reaction of formaldehydeyielding formic acid and hydrogen may not be an elementary reaction.The dehydrogenation of ethoxy possesses the highest barrier and isaccordingly identified as the rate-determining step. [ABSTRACT FROM AUTHOR]

Abstract: Reducing anthropogenic CO2 emission and lowering the concentration of greenhouse gases in the atmosphere has quickly become one of the most urgent environmental issues of our age. Carbon capture and storage (CCS) is one option for reducing these harmful CO2 emissions. While a variety of technologies and methods have been developed, the separation of CO2 from gas streams is still a critical issue. Apart from establishing new techniques, the exploration of capture materials with high separation performance and low capital cost are of paramount importance. Metal-organic frameworks (MOFs), a new class of crystalline porous materials constructed by metal-containing nodes bonded to organic bridging ligands hold great potential as adsorbents or membrane materials in gas separation. In this paper, we review the research progress (from experimental results to molecular simulations) in MOFs for CO2 adsorption, storage, and separations (adsorptive separation and membrane-based separation) that are directly related to CO2 capture. [Copyright &y& Elsevier]

Abstract: Surface segregation of Pt3M (M=Fe, Co, and Ni) alloys under oxygen environment has been examined using periodic density functional theory. The segregation trend at a (111) surface is found to be substantially modified by the adsorbed oxygen. Our calculations indicate that under 1/4 monolayer O coverage both the Pt-segregated and M-segregated surfaces are less stable than the non-segregated one. Further analysis reveals that segregation energy under adsorption environments can be expressed as the sum of the segregation energy under vacuum conditions and the adsorption energy difference of the segregated and non-segregated alloy systems. Therefore, the surface segregation trend under adsorption conditions is directly correlated to the surface-adsorbate binding strength. [Copyright &y& Elsevier]

Abstract: A simplified 5-layer slab model is used to study Pt segregation at Pt3M(111) surfaces (M=Ag, Au, Co, Cr, Cu, Fe, Ir, Mn, Mo, Ni, Pd, Re, Rh, Ru, Ti, V). The calculated segregation energies are generally in good agreement with the experimental results. However, for Pt3Ti(111) and Pt3Mn(111), the model is unable to give the correct prediction because the experimental subsurface compositions are very different from those of the model. Pt segregation is found to be correlated with the subsurface atomic structure, the size of metal atoms and the surface energy. Interestingly, the calculations show that the displacement of M atoms at the topmost Pt3M layer can be used to predict the surface segregation trend. The local geometries for the segregation and non-segregation structures are carefully compared and the surface geometric effect on the oxygen reduction reaction (ORR) activity is discussed. In particular, it is determined that the enhanced ORR activity for the Pt-skin surfaces of Pt3Ni(111) and Pt3Co(111) alloys are not caused by geometric effects. [Copyright &y& Elsevier]

Abstract: OOH dissociation on Pt2, Pt3, Pt4, Pt7 and Pt12 clusters is studied using density functional theory. The activation energy varies widely with the size and geometry of the clusters, from 2.23kcal/mol for Pt2 to 13.9kcal/mol for Pt12. Calculations on a single-layer Pt12 used to emulate surface, edge, and corners of Pt(111) nanoparticles reveal that the energy barrier depends significantly on the adsorbate position on the cluster. The edge adsorption sites exhibit the highest catalytic activity. A correlation between the activation energy and the Pt–Pt distance suggests that the dissociation reaction can be facilitated by increasing the Pt–Pt distance. [Copyright &y& Elsevier]

Abstract: A complete catalytic cycle for H2 oxidation on a model emulating the active site of Fe-only hydrogenases, [Fe2(μ-DTMA)(CO)4(CN)2]2− (DTMA=SCH2NHCH2S), has been investigated using density functional theory (DFT). Our calculations show that the bridged CO group in the fully reduced species does not play a significant role on the H2 activation. According to the studied mechanism, the rate-determining step is neither kinetically nor thermodynamically favorable for the second proton transfer. A modified model aiming to improve the catalytic efficiency has been designed and a plausible catalytic mechanism is suggested. In the new model, [Fe2(μ-PDTN)(CO)4(CN)2]2− (PDTN=SCH2CH(NH2)CH2S), a shorter proton transfer path has been obtained by changing the base position and the process is significantly facilitated. In the modified catalytic cycle, the highest barrier for H2 oxidation is only 7.90kcalmol−1. [Copyright &y& Elsevier]

Abstract: A thermodynamic analysis using density functional theory suggests a parallelism between the mechanisms of cytochrome c oxidase and that of a bimetallic alloy catalyst for reducing oxygen to water. It is shown that ionic sites such as those in enzymes are thermodynamically more favorable than neutral atoms composing the alloy to catalyze specific reaction steps. The potential for designing novel effective oxygen reduction catalysts is discussed. [Copyright &y& Elsevier]

We present a B3PW91/6-31G** computational procedure for predicting standard gas phase heats of formation at 298.15 K by finding ΔH for the process whereby the molecule is produced from its elements and then adding empirical atomic correction terms. Heats of vaporization and sublimation are estimated on the basis of the calculated electrostatic potential on the molecular surface. These results permit prediction of the standard liquid and solid-phase heats of formation. In comparison with experimental data, the average absolute deviations are as follows: for the heats of formation, gas phase, 2.6 kcal/mol; liquid phase, 2.4 kcal/mol; solid phase, 3.8 kcal/mol; for the heats of vaporization, 2.0 kcal/mol; and for the heats of sublimation, 2.8 kcal/mol. Computed values of these properties are given for a number of compounds for which they are not available experimentally. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [ABSTRACT FROM AUTHOR]

A methodology for using electronic densities to determine electrostatic, polarization, and total energies of noncovalent interactions is summarized and applied to two key molecular pair combinations in the crystal lattice of RDX (hexahydro‐1,3,5‐trinitro‐s‐triazine). It is found that the total interaction energies can be well approximated as purely electrostatic between RDX molecules in the chair–AAE conformation. However, Mulliken and CHelpG point‐charge models are not adequate for reproducing these energies. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 [ABSTRACT FROM AUTHOR]

It is crucial to prepare high-mobility organic polycrystalline film through solution processing. However, the delocalized carrier transport of polycrystalline films in organic semiconductors has rarely been investigated through Hall-effect measurement. This study presents a strategy for building strong intermolecular interactions to fabricate solution-crystallized p-type perylene diimide (PDI) dianion films with a closer intermolecular π–π stacking distance of 3.25 Å. The highly delocalized carriers enable a competitive Hall mobility of 3 cm2 V−1 s−1, comparable to that of the reported high-mobility organic single crystals. The PDI dianion films exhibit a high electrical conductivity of 17 S cm−1 and typical band-like transport, as evidenced by the negative temperature linear coefficient of mobility proportional to T −3/2. This work demonstrates that, as the intermolecular π–π interactions become strong enough, they will display high mobility and conductivity, providing a new approach to developing high-mobility organic semiconductor materials. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Doping plays an essential role in the properties of conducting polymers. Film thickness not only has a direct influence on their photoelectric properties, but also affects the doping ability, which may lead to the decline of capacitance and electrochromic properties caused by incomplete doping. Therefore, it is essential to study the quantitative relationship between doping level and film thickness in application. Herein, empirical formula between doping level and thickness was obtained by studying the spectroelectrochemistry behaviors of two different electrochromic materials, poly(N,N'‐bis(3,5‐(2‐thienyl)‐phenyl)‐1,6,7,12‐tetrachloroperylene‐3,4,9,10‐perylenetetracarboxylic diimide) (poly(Th‐Cl‐PBI)) and poly(3,4‐ethylenedioxythiophene) (PEDOT). The doping level is verified to be correlated to the reciprocal of the 3rd power of film thickness. Experimental results fit these formulas very well, giving correlation coefficient R2 higher than 0.99. The optical contrast prediction of these two electrochromic materials is also used to verify this relationship formula. For the first time, we quantitatively connect these two important parameters of conducting polymers, doping level and thickness. [ABSTRACT FROM AUTHOR]

Triplet‐triplet fusion (TTF) can effectively transfer triplet excitons to singlet energy level and exhibit good stability, making it widely used in blue fluorescence organic light emitting diodes (OLEDs) for practical application. However, the efficiency of the resulting blue fluorescence OLEDs is still fundamentally limited. Herein, this work introduces a hot exciton efficiency enhancement layer (EEL) between TTF emissive layer and electron‐transporting layer for the first time. It can be found that the triplet excitons are greatly utilized by the efficient hot exciton EEL. As a result, a high efficiency blue fluorescence OLED is successfully developed, exhibiting a maximum external quantum efficiency of 15.2% at the luminance of 4068.0 cd m−2, achieving a breakthrough in the efficiency of blue TTF‐OLEDs. Transient electroluminescence (TrEL) measurements and detailed theoretical calculations confirm the key role of the effective hot exciton process from the high‐lying triplet energy level (Tn, n ≥ 2) to S1 via a reverse intersystem crossing (hRISC). Furthermore, the device lifetime is also greatly improved owing to the fast and efficient hRISC in the introduced hot exciton EEL. This work has important guiding significance for constructing high efficiency blue fluorescence OLEDs by introducing hot exciton molecules. [ABSTRACT FROM AUTHOR]

Excellent stability is an essential premise for organic diradicals to be used in organic electronic and spintronic devices. We have attached two tris(2,4,6‐trichlorophenyl)methyl (TTM) radical building blocks to the two sides of perylene bisimide (PBI) bridges and obtained two regioisomeric diradicals (1,6‐TTM‐PBI and 1,7‐TTM‐PBI). Both of the isomers show super stability rather than the monomeric TTM under ambient conditions, due to the increased conjugation and the electron‐withdrawing effects of the PBI bridges. The diradicals show distinct and reversible multistep redox processes, and a spectro‐electrochemistry investigation revealed the generation of organic mixed‐valence (MV) species during reduction processes. The two diradicals have singlet ground states, very small singlet–triplet energy gaps (ΔES‐T) and a pure open‐shell character (with diradical character y0=0.966 for 1,6‐TTM‐PBI and 0.967 for 1,7‐TTM‐PBI). This work opens a window to developing very stable diradicals and offers the opportunity of their further application in optical, electronic and magnetic devices. [ABSTRACT FROM AUTHOR]

In contrast to edge‐on and face‐on orientations, end‐on uniaxial conjugated polymers have the theoretical possibility of providing a macroscopic crystalline film. However, their fabrication is insurmountable due to sluggishly thermodynamic equilibrium states. Herein, we report the programmatic pathway to fabricate nanoarchitectonics on end‐on uniaxial conjugated metallopolymers by surface‐initiated simultaneous electrosynthesis and assembly. Self‐assembled monolayer (SAM) with bottom‐up oriented electroactive molecules as a temple allows orientation, stacking, and reactive addition of monomers triggered by switching alternative redox reactions as well as crystallization of small molecules. Repeating the same reaction can repair the unreactive site on the SAM and dynamically and statistically ensure maximum iterative coverage with ideal linear coefficients between optical or electrical responses and iterative times. The resulting nanoarchitectonics on uniaxially assembled end‐on polymers over centimeter‐sized areas have a subnanometer‐uniform morphology and exhibit ultrahigh modulus as well as an inorganic indium tin oxides and the highest conductance among conjugated molecular monolayers. Their memristive devices provide quantitative electrical and optical responses as a function of molecular length, bias, and iterative junctions. Precise processing of nanoarchitectonics as an electrically assisted assembly or printing technique can present sophisticated optoelectric functions and dimensional batch‐to‐batch consistency for micro‐sized organic materials and electronics. [ABSTRACT FROM AUTHOR]

In contrast to edge‐on and face‐on orientations, end‐on uniaxial conjugated polymers have the theoretical possibility of providing a macroscopic crystalline film. However, their fabrication is insurmountable due to sluggishly thermodynamic equilibrium states. Herein, we report the programmatic pathway to fabricate nanoarchitectonics on end‐on uniaxial conjugated metallopolymers by surface‐initiated simultaneous electrosynthesis and assembly. Self‐assembled monolayer (SAM) with bottom‐up oriented electroactive molecules as a temple allows orientation, stacking, and reactive addition of monomers triggered by switching alternative redox reactions as well as crystallization of small molecules. Repeating the same reaction can repair the unreactive site on the SAM and dynamically and statistically ensure maximum iterative coverage with ideal linear coefficients between optical or electrical responses and iterative times. The resulting nanoarchitectonics on uniaxially assembled end‐on polymers over centimeter‐sized areas have a subnanometer‐uniform morphology and exhibit ultrahigh modulus as well as an inorganic indium tin oxides and the highest conductance among conjugated molecular monolayers. Their memristive devices provide quantitative electrical and optical responses as a function of molecular length, bias, and iterative junctions. Precise processing of nanoarchitectonics as an electrically assisted assembly or printing technique can present sophisticated optoelectric functions and dimensional batch‐to‐batch consistency for micro‐sized organic materials and electronics. [ABSTRACT FROM AUTHOR]

Organic photodetectors have attracted increasing attention in the scenario of low-cost imaging, health monitoring, and near-infrared sensing. However, relatively high dark current and trap density block the sensitivity for organic photodetectors. In this manuscript, a simple yet effective strategy is proposed to enhance the detectivity of organic photodetectors by incorporating a non-conjugated polymer additive of polystyrene into the functional layers. Systematic morphological investigation reveals that this strategy can not only enable suppressed amorphous phase but also effectively tune the phase separation in the bulk heterojunction blends. Electrical results suggest the suppressed trap density in optimized organic photodetectors. Consequently, a dark current density of 5.06 × 10−10 A cm−2 is achieved for PM6:Y6-BO-based organic photodetectors, showing a peak detectivity of 6.38 × 1013 cm Hz1/2 W−1 at 850 nm. This strategy is also applicable in various representative organic-semiconductor systems, including PTB7-Th:PC71BM and P3HT:PC61BM blends, superior to other optimization techniques. [ABSTRACT FROM AUTHOR]

The operational lifetime of blue organic light‐emitting diodes (OLEDs) is still insufficient for practical applications in lighting and display. One type of blue organic emitting materials with hybridized local and charge‐transfer (HLCT) process are beneficial in achieving high‐efficiency OLEDs through "hot exciton" channel by harnessing high‐lying triplet (Tn) excitons. However, the operational lifetime of the resulting blue OLEDs is rarely studied and understood. In this article, the aging properties of blue fluorescent OLEDs based on an HLCT material (2‐(4‐(10‐(3‐(9H‐carbazol‐9‐yl)phenyl)anthracen‐9‐yl)phenyl)‐1‐phenyl‐1H‐phenanthro[9,10‐d]imidazole) (PAC) are systematically investigated by exciton dynamics calculation and transient EL experiments. It is experimentally and theoretically revealed that whether the reverse intersystem crossing (hRISC) process from high‐lying excited triplet to singlet in HLCT materials is completely effective determines the device degradation. A fluorescent emitter is doped into PAC host to accelerate the hRISC process, thus enhancing device operational lifetime to reach T75 = 110 ± 2 h (time to 75% of initial luminance) under 1000 cd m−2. This work provides inspirations to investigate the stability of blue fluorescent OLEDs based on HCLT materials and further enhance the operational lifetime. [ABSTRACT FROM AUTHOR]

Sulfone‐embedded heterocyclics are of great interest in organic light‐emitting diodes (OLEDs), however, exploring highly efficient narrowband emitters based on sulfone‐embedded heterocyclics remains challenging. Herein, five emitters with different sulfur valence state and molecular rigidity, namely tP, tCPD, 2tCPD, tPD and tPT, are thoroughly analysed. With restricted twisting of flexible peripheral phenyl by strengthening molecular rigidity, molecular emission spectra can be enormously narrowed. Further, introducing the sulfone group with bending vibration in low‐frequency region that suppresses high‐frequency vibration, sharp narrow full‐widths at half‐maximum of 28 and 25 nm are achieved for 2tCPD and tPD, respectively. Maximum external quantum efficiencies of 22.0 % and 27.1 % are successfully realized for 2tCPD‐ and tPD‐based OLED devices. These results offer a novel design strategy for constructing narrowband emitters by introducing sulfone group into a rigid molecular framework. [ABSTRACT FROM AUTHOR]

Sulfone‐embedded heterocyclics are of great interest in organic light‐emitting diodes (OLEDs), however, exploring highly efficient narrowband emitters based on sulfone‐embedded heterocyclics remains challenging. Herein, five emitters with different sulfur valence state and molecular rigidity, namely tP, tCPD, 2tCPD, tPD and tPT, are thoroughly analysed. With restricted twisting of flexible peripheral phenyl by strengthening molecular rigidity, molecular emission spectra can be enormously narrowed. Further, introducing the sulfone group with bending vibration in low‐frequency region that suppresses high‐frequency vibration, sharp narrow full‐widths at half‐maximum of 28 and 25 nm are achieved for 2tCPD and tPD, respectively. Maximum external quantum efficiencies of 22.0 % and 27.1 % are successfully realized for 2tCPD‐ and tPD‐based OLED devices. These results offer a novel design strategy for constructing narrowband emitters by introducing sulfone group into a rigid molecular framework. [ABSTRACT FROM AUTHOR]

The reverse intersystem crossing (RISC) process from triplet to singlet manifold can efficiently improve the efficiencies of organic light‐emitting diodes (OLEDs). The relevant RISC rate (kRISC) is one of the key factors that affect the efficiency roll‐off and stability of devices. Here, a new blue "hot exciton" material, CPPCN, with pyrene as the core, is designed and synthesized. Photophysical studies indicate there are multiple high‐lying triplet states near the lowest singlet excited state (S1) of CPPCN, which facilitate the RISC from the high‐lying triplet state (hRISC) to the S1 state. The corresponding hRISC rate constant is determined to be as high as 2.86 × 108 s−1, a value some two to three orders of magnitude higher than typical thermally activated delayed fluorescence materials emitters. Benefiting from this ultrafast hRISC process, non‐doped blue OLED based on CPPCN reaches a high maximum external quantum efficiency (EQE) of 11.64% with suppressed efficiency roll‐off (begin roll‐off at a high brightness of 3732 cd m−2 and retains EQE >8.5% at 10 000 cd m−2). The T95 lifetime of the CPPCN‐based device with a structure of commercial applications is evaluated to be ≈368 h at 1000 cd m−2. [ABSTRACT FROM AUTHOR]

The polytriphenylamine films are prepared by electropolymerization from a precursor HPB‐6TPA with hexaphenylbenzene (HPB) core bearing six triphenylamine (TPA) units. The abundant and valuable electrochromism from transparent to black and from no to strong near‐infrared absorption are achieved from this TPA network film. The presence of residual TPA and dimeric TPA (N,N,N′,N′‐tetraphenylbenzidine) units in network film and their independent potential response attain the electrochromic behaviors. The network film possesses short response time and can realize high doping level (72%), attributed to favorable dopant ion channel caused by the twisting structure of HPB core and TPA units. The network film also shows large lightness changes and high specific capacitance (788.9 F g−1@1.4 A g−1), attributed to multiple active units due to HPB core with high functionality. By regulating the voltammetric cycle number of electropolymerization, films with different lightness black colored states can be prepared conveniently to satisfy different practical needs. [ABSTRACT FROM AUTHOR]

Spintronics, a new discipline focusing on the spin‐dependent transport process of electrons, has been developing rapidly. Spin valves are the most significant carriers of spintronics utilizing the spin freedom of electrons. It is expected to pierce "Moore's Law" and become the core component in processors of the next generation. Organic semiconductors advance in their adjustable band gap, weak spin‐orbit coupling and hyperfine interaction, excellent film‐forming property, having enormous promise for spin valves. Here, the principle of spin valves is introduced, and the history and progress in organic spin injection and transport materials are summarized. Then we analyze the influence of spinterface on device performance and introduce reliable methods of constructing organic spin valves. Finally, the challenges for spin valves are discussed, and the future is proposed. We aim to draw the attention of researchers to organic spin valves and promote further research in spintronics through this paper. [ABSTRACT FROM AUTHOR]

Crystalline thin‐film organic light‐emitting diodes (C‐OLEDs) can achieve a large light emission and a low Joule‐heat loss under low driving voltage due to the high carrier mobility of the crystalline thin films. However, it is urgent for the C‐OLEDs to improve their external quantum efficiency (EQE). Here, a novel strategy is proposed using a doped "hot exciton" material to sensitize a high PLQY blue emitter in C‐OLEDs. Benefiting from the capability of the "hot exciton" material harnessing triplet/singlet excitons, the C‐OLED exhibits an efficiency breakthrough with a maximum EQE of 6.2%, a much enhanced blue photon output with pure blue emission Commission International de L'Eclairage (CIE) (0.14, 0.15), a low turn‐on/operation voltage of 2.6 V(@1 cd m−2)/3.8 V (@1000 cd m−2), and a maximum power efficiency (PE) of 9.4 lm W−1. This work unlocks the potential of C‐OLEDs for achieving high photon output with high EQE. [ABSTRACT FROM AUTHOR]

Several studies have shown that female reproductive factors are associated with breast cancer (BC), but the results differ. We conducted two-sample MR in the present work. The raw data applied in the MR study were all from the Genome-wide association study (GWAS) database. The causal effect of reproductive factors on breast cancer were mainly estimated by the standard inverse variance weighted (IVW) method. Cochran's Q test and I2 statistics were used to assess heterogeneity. The pleiotropy was evaluated by MR-Egger intercept test and MR-PRESSO. Finally, the leave-one-out analysis was performed to evaluate the robustness of the MR results. We found that there was a negative causal effect of the age at last live birth on BC (OR = 0.687, 95%CI = 0.539–0.875, p = 0.002) and positive effect of the age at menopause on BC (OR = 1.054, 95%CI = 1.034–1.075, p = 8.010 × 10−8). Additionally, there were null effects of the age at menarche (OR = 0.977, 95%CI = 0.915–1.043, p = 0.484), the age at first sexual intercourse (OR = 1.053, 95%CI = 0.958–1.157, p = 0.284) and the age at first birth (OR = 0.981, 95%CI = 0.936–1.027, p = 0.404) on BC. All these results were reliable and stable. In conclusion, the present study showed that younger age at last birth and older age at menopause could increase the risk of BC. [ABSTRACT FROM AUTHOR]

It is well‐known that the electrically generated excitons can perform the spin evolution between high‐lying excited states, providing an efficient way to utilize triplet excitons in organic light‐emitting diodes (OLEDs). Anthracene families offer an opportunity to deeply investigate the processes of triplet excitons on high‐lying excited states in detail. Here, a simplified model is proposed to study the exciton dynamics in anthracene derivatives‐based devices. The mechanism on the processes of high‐energy level intersystem crossing in anthracene derivatives is well revealed by theoretical calculation, transient electroluminescence, transient photoluminescence, and transient absorption spectrum measurements. Besides, doping strategy is proposed to suppress the exciton loss channel for improving the efficiency of devices. The studies establish an in situ method to evaluate the apparent singlet exciton formation ratio in devices due to the exciton evolution between high‐lying excited states and offer some clues to further utilize these triplet excitons, thus improving the efficiency of the resulting fluorescence OLEDs in the future. [ABSTRACT FROM AUTHOR]

Five 3,5-difluorophenyl-substituted ruthenium complexes [Ru(bpy)2(dfpbpy)(ClO4)2] (Ru-Fbpy-bpy; bpy=bipyridine, dfpbpy=5,5′-di(3,5-difluorophenyl)-2,2′-bipyridine), [Ru(dpp)2(dfpbpy)(ClO4)2] (Ru-Fbpy-dpp; dpp=4,7-diphenyl-1,10-phenanthroline), [Ru(dpp)2(dfpphen)(ClO4)2] (Ru-Fphen-dpp; dfpphen=5,5′-di(3,5-difluorophenyl)-1,10-phenanthroline), [Ru(dpp)2(4,7-dfpphen)(ClO4)2] (Ru-Fdpp-dpp; 4,7-dfpphen=4,7-di(3,5-difluorophenyl)-1,10-phenanthroline), and [Ru(4,7-dfpphen)3(AsF6)2] (Ru-Fdpp) were synthesized, and their photophysical, electrochemical, and electroluminescent properties were studied systematically. The introduction of the electron-withdrawing group 3,5-difluorophenyl leads to a redshift of the emission of the ruthenium complexes. In addition, the 3,5-difluorophenyl substituent extends the π conjugation of the ligand, and thus facilitates the metal-to-ligand charge-transfer process of the complexes. All the complexes display orange-red phosphorescent emissions centered at 638, 638, 624, 614, and 605 nm, respectively. Density functional theory calculations show that the lowest unoccupied molecular orbital of Ru-Fbpy-dpp, Ru-Fphen-dpp, and Ru-Fdpp-dpp are all distributed on the 3,5-difluorophenyl-substituted ligand. By using these complexes as emitters, highly luminescent single-layer devices are obtained. The optimized device based on Ru-Fdpp exhibits the highest luminous efficiency and power efficiency of 4.19 cd A−1 and 1.46 lm W−1, respectively. [ABSTRACT FROM AUTHOR]

Organic materials with excitation wavelength‐dependent (Ex‐de) emission are highly attractive for anticounterfeiting, optoelectronics and bioassay applications; however, the realization of Ex‐de fluorescence, independent of aggregation states, remains a challenge. We herein report a photoinduced electron transfer (PeT) strategy to design Ex‐de fluorescence materials by manipulating the relaxation pathways of multiple excited states. As expected, the o‐carborane dyad presents a clear Ex‐de fluorescence colour in the aggregated states, resulting from the tunable relative intensity of the dual‐fluorescence spectra. Taking TP[1]B as an example, the amorphous powders emitted bright blue‐violet, white and yellow colours under 390 nm, 365 nm and 254 nm UV illumination, respectively. Importantly, multicolour, flexible and transparent films as well as an anticounterfeiting application using this o‐carborane dyad are demonstrated. [ABSTRACT FROM AUTHOR]

Organic materials with excitation wavelength‐dependent (Ex‐de) emission are highly attractive for anticounterfeiting, optoelectronics and bioassay applications; however, the realization of Ex‐de fluorescence, independent of aggregation states, remains a challenge. We herein report a photoinduced electron transfer (PeT) strategy to design Ex‐de fluorescence materials by manipulating the relaxation pathways of multiple excited states. As expected, the o‐carborane dyad presents a clear Ex‐de fluorescence colour in the aggregated states, resulting from the tunable relative intensity of the dual‐fluorescence spectra. Taking TP[1]B as an example, the amorphous powders emitted bright blue‐violet, white and yellow colours under 390 nm, 365 nm and 254 nm UV illumination, respectively. Importantly, multicolour, flexible and transparent films as well as an anticounterfeiting application using this o‐carborane dyad are demonstrated. [ABSTRACT FROM AUTHOR]

Electrochemical deposition has emerged as an efficient technique for preparing conjugated polymer films on electrodes. However, this method encounters difficulties in synthesizing crystalline products and controlling their orientation on electrodes. Here we report electrochemical film deposition of a large polycyclic aromatic hydrocarbon. The film is composed of single‐crystalline nanorods, in which the molecules adopt a cofacial stacking arrangement along the π–π direction. Film thickness and crystal size can be controlled by electrochemical conditions such as scan rate and electrolyte species, while the choice of anode material determines crystal orientation. The film supports exceptionally efficient migration of both free carriers and excitons: the free carrier mobility reaches over 30 cm2 V−1 s−1, whereas the excitons are delocalized with a low binding energy of 118.5 meV and a remarkable exciton diffusion length of 45 nm. [ABSTRACT FROM AUTHOR]

Electrochemical deposition has emerged as an efficient technique for preparing conjugated polymer films on electrodes. However, this method encounters difficulties in synthesizing crystalline products and controlling their orientation on electrodes. Here we report electrochemical film deposition of a large polycyclic aromatic hydrocarbon. The film is composed of single‐crystalline nanorods, in which the molecules adopt a cofacial stacking arrangement along the π–π direction. Film thickness and crystal size can be controlled by electrochemical conditions such as scan rate and electrolyte species, while the choice of anode material determines crystal orientation. The film supports exceptionally efficient migration of both free carriers and excitons: the free carrier mobility reaches over 30 cm2 V−1 s−1, whereas the excitons are delocalized with a low binding energy of 118.5 meV and a remarkable exciton diffusion length of 45 nm. [ABSTRACT FROM AUTHOR]

Hot excitons have been attempted to utilize the triplet excitons in organic light-emitting diodes (OLEDs). Due to the transient and dark nature of high-lying triplet states (Tn, n ≥ 2), the normative methods to characterize the hot exciton mechanism have not been thoroughly developed. Here, a normal technique combining transient photoluminescence and magneto-electroluminescence (MEL) measurements has been proven to visualize the reverse intersystem crossing process from T2 to S1 states in 5,6,11,12-tetraphenylnaphthacene (rubrene) molecules. Rubrene is chosen as a model system since its T1 is far below S1 and T2 is resonant with S1. This hot exciton process opens an additional route, marked as Dexter energy transfer channel ( CT 3 → T 2 → S 1 , DET channel), together with the well-known Förster resonance energy transfer channel ( CT 1 → S 1 ) to transfer the host energy to the guest. With proper approximates, the DET channel assisted by the hot excitons process can contribute about 46.6% excitons to rubrene S1 and 83.4% rubrene emission in rubrene-doped devices. These studies set an in situ normative characterizing frame to visualize the hot excitons process in OLEDs. [ABSTRACT FROM AUTHOR]

Abstract: Ultrasound-assisted synthesis of conjugated polymer is reported taking PF as an example. It is found that ultrasound can dramatically accelerate the Suzuki coupling reaction. The effects of ultrasonic amplitude, time, monomer and catalyst's concentration on the polymerization have been investigated. PF with high M w of 39,100 g/mol is obtained in 20 min under optimized condition. [Copyright &y& Elsevier]

"Hot exciton" luminescent materials are being researched as potential candidates for application in OLEDs due to their ability to undergo high-level reverse intersystem crossing (hRISC). While evaporated OLEDs using "hot exciton" luminescent materials have shown impressive efficiency, there is a dearth of information on solution-processed "hot exciton" OLEDs, specifically in the realm of deep blue OLEDs. In this work, we developed novel solution-processed blue OLEDs by employing "hot exciton" material, 2-(4-(10-(3-(9H-carbazol-9-yl)phenyl) anthracen-9-yl)phenyl)-1-phenyl-1H-phenanthro [9,10-d] imidazole (PAC), as the luminescent material and host material (the classical fluorescent material BD as a guest). An improvement to the quantum efficiency of the luminescent layer was achieved by incorporating a hole transport layer (PVK) between the hole injecting layer (PEDOT:PSS:PFI) and the luminescent layer. Finally, the resultant non-doped blue OLED achieved EQE max and EUE max of 4.5 % and 56.3 %, respectively, while the doped blue OLED showed EQE max and EUE max of 5.3 % and 54.8 %, respectively. The efficiency roll-off at a brightness of 1000 cd m−2 for the doped device was 11.5 %, whereas for the non-doped device was only 4.2 %. Analysis of the magneto-electroluminescence and transient EL decay suggests that the high EUE in the solution-processed devices primarily derives from the "hot exciton" process. This study confirms that "hot exciton" materials can serve as a key factor in achieving efficient solution-processed blue OLEDs through a well-designed device architecture. • Solution-processed blue OLEDs are prepared with "hot excition" material as luminescent material and host material. • The OLEDs exhibit superior external quantum efficiency and exciton utilization efficiency. • The incorporation of PVK as an intermediate layer enhances the photoluminescence quantum yields (PLQYs) of the luminescent layer. • The doped OLED exhibits a minimum efficiency drop of 4.2% at a brightness of 1000 cd m-2. [ABSTRACT FROM AUTHOR]

Compositing gold nanoparticles into conjugated molecules have been developed to be one of the most important approaches to increase stability, since degradation of conjugated materials is now one of the biggest bottle-necks to be conquered before industrialization application. Big-size colloidal gold nanoparticles with strong surface plasma resonance are designed to composite with conjugated molecules, in order to realize effective fluorescence enhancement and stabilization. The uniform composition film of hydrophilic colloidal gold nanoparticles (particle diameter of 30 nm) and hydrophobic carbazole functionalized fluorene trimers has been obtained by direct mixing of their aqueous and THF solutions, which is determined by AFM. By the comparison of composition based on fluorene trimers with similar structures, we have found that peripheral carbazole group and molecular size of fluorene trimers play an important role in the balance of incompatible solubility, which is regarded as increasing solubility of fluorene trimers in mixed solvent, connecting AuNP and peripheral carbazole groups, and restraining aggregate of gold nanoparticle. This allows facile hydrophilic gold nanoparticle to disperse uniformly in hydrophobic π-conjugated host. Our investigations show that fluorescence intensity of composition film is enhanced by 4 folds, and heat treatment (200°C for 4 h) for the composition film does not induce the degradation of conjugated backbone without the appearance of low-energy emission band, demonstrating the prominent potency of gold nanoparticles in enhanced fluorescence and stability of conjugated molecules and polymers. [ABSTRACT FROM AUTHOR]

Aggregation‐induced emission (AIE) and hybridized local and charge‐transfer (HLCT) materials are two kinds of promising electroluminescence systems for the fabrication of high‐efficiency organic light‐emitting diodes (OLEDs) by harnessing "hot excitons" at the high‐lying triplet exciton states (Tn, n ≥ 2). Nonetheless, the efficiency of the resulting OLEDs did not meet expectations due to the possible loss of Tn→Tn−1. Herein, experimental results and theoretical calculations demonstrate the "hot exciton" process between the high‐lying triplet state T3 and the lowest excited singlet state S1 in an AIE material 4⁗‐(diphenylamino)‐2″,5″‐diphenyl‐[1,1″:4′,1″:4″,1′″:4′″,1⁗‐quinquephenyl]‐4‐carbonitrile (TPB‐PAPC) and it is found that the Förster resonance energy transfer (FRET) between two molecules can facilitate the "hot exciton" process and inhibit the T3→T2 loss by doping a blue fluorescent emitter in TPB‐PAPC. Finally, the doped TPB‐PAPC blue OLEDs achieve a maximum external quantum efficiency (EQEmax) of 9.0% with a small efficiency roll‐off. Furthermore, doping the blue fluorescent emitter in a HLCT material 2‐(4‐(10‐(3‐(9H‐carbazol‐9‐yl)phenyl)anthracen‐9‐yl)phenyl)‐1‐phenyl‐1H‐phenanthro[9,10‐d] imidazole (PAC) is used as the emission layer, and the resulting blue OLEDs exhibit an EQEmax of 17.4%, realizing the efficiency breakthrough of blue fluorescence OLEDs. This work establishes a physical insight in the design of high‐performance "hot exciton" molecules and the fabrication of high‐performance blue fluorescence OLEDs. [ABSTRACT FROM AUTHOR]

Abstract: The hydrogenation/hydrodeoxygenation of furfural was studied on a Cu/SiO2 catalyst at 230–290°C. Detailed kinetics, density function (DFT) calculations, and spectroscopic studies were combined to investigate this reaction. A Langmuir–Hinshelwood model was found to fit the kinetic data well and provided the parameters of physical significance. The heat of adsorption (ΔHads ) of furfural, derived from the fitting, was found to be significantly higher than those of furfuryl alcohol and 2-methyl furan. Activation energies for the conversion of furfural and furfuryl alcohol were both about 12kcal/mol. DFT calculations and DRIFTS provided guidance about the nature of the surface species. Accordingly, the most likely species adsorbed on the Cu surface is suggested to be a top η 1(O)-aldehyde. DFT calculations of the reaction path show that the predicted energy barriers are of the same order as the experimental values and suggest that the hydrogenation of furfural can occur via either an alkoxide or ahydroxyalkyl intermediate. [ABSTRACT FROM AUTHOR]

The poly(p-phenylenevinylene–styrene) block copolymers (PPV-co-PS) have good solubility and fabrication. The photoluminescence (PL) properties of the PPV-co-PS block copolymers in chloroform solution and in solid film were studied. The PL spectra of the PPV-co-PS copolymers in chloroform were gradually blue-shifted from 501 to 431 nm with increasing of the PS content in the PPV-co-PS copolymers, which contributed to the shortening of the PPV conjugation length in the copolymers. The single-layer electroluminescence (EL) device fabricated from the copolymer showed the emission blue light and the low turn-on voltage at 8.0 V. Also, the emission peaks were blue-shifted with increasing of the applied voltage, which might be contributed by different conjugation lengths in the copolymers. [Copyright &y& Elsevier]

Organic fluorescent emitters with narrowband emissions are highly desirable for high‐resolution organic light‐emitting diode (OLED) display technology. In principle, this can be achieved by specifically controlling the intrinsic structural relaxation and vibronic coupling in the excited state. Here, a design strategy to realize narrowband emission of organic fluorescent emitters is proposed by significantly enhancing the low‐frequency vibronic coupling strength (Λ) while simultaneously reducing the high‐frequency Λ of the commonly involved stretching modes. The quinolino‐[3,2,1‐de]acridine‐5,9‐dione (QAO) species is found to be directly associated with this design principle. By introducing single bond‐linked peripheral moieties into the QAO core, the constructed QAO derivatives are shown to exhibit better performance, by achieving a full width at half‐maximum of 23 nm/0.13 eV in toluene for the narrowest band as well as 27 nm/0.15 eV in doped devices, with negligible dependence on the doping concentrations. The maximum external quantum efficiency of the fabricated blue OLED is 17.5%. [ABSTRACT FROM AUTHOR]

[Display omitted] • An intramolecular dual-locking design is proposed for multifunctional "hot exciton" emitters. • A new donor–acceptor molecule (LPCz-TRZ) with appreciable global rigidity and local flexibility is synthesized. • A high-contrast, fatigue-resistance data-recording device is demonstrated with LPCz-TRZ. • A high-performance deep-blue OLED with an external quantum efficiency as high as 7.88% is realized. An intramolecular dual-locking design is proposed for organic luminescent materials, aiming at synergistically adjusting the molecular rigidity and flexibility for applications in data storage and light-emitting devices. According to this concept, a multifunctional donor–acceptor type emitter, LPCz-TRZ, is developed, featuring a "soft" diphenylmethane lock and a "hard" single-bond lock in its donor moiety. The highly locked structure results in appreciable rigidity that endows LPCz-TRZ with high luminescence efficiency, narrow emission, promoted charge conductivity and triplet harvesting "hot exciton" channels, allowing high-performance deep-blue organic light-emitting diodes (OLEDs) with an external quantum efficiency as high as 7.88%, which is among the best deep-blue "hot exciton" OLEDs. Notably, the structure of LPCz-TRZ is semi-flexible, leading to unique mechanochromic luminescence (MCL) behavior. Compared to the conventional MCL emitters, the orchestration of rigidity and flexibility in LPCz-TRZ affords high-contrast, fatigue-resistance MCL, as evidenced by a simple, rewritable data-recording demonstration with negligible fatigue after up to 15 wiring-erasing cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • PYHB and PYHP deliver excellent thermal stability and morphological stability. • PYHB and PYHP can inherit the narrowband blue emission and HLCT characteristics. • PYHB and PYHP remove the limitations of traditional polymer luminescent materials. • PYHB and PYHP outperform previously reported polymer luminescent materials. • Our strategy provides a promising platform for PIs as a photoelectric material. Blue light-emitting materials with excellent film-forming ability, superior morphological stability, outstanding color purity, and high device efficiency are in urgent demand for new-generation display and solid-state lighting devices fabricated by low-cost wet processing. However, their current performances are far from satisfactory. Herein, two polyimide (PI)-based blue polymers are first precisely constructed and synthesized through a "Hinge-type Linking" strategy. A small molecular is introduced into the PI backbone via non-conjugated aliphatic imide ring linker. These polymers not only show superb thermal stability and morphological stability, but also maintain narrowband blue emission. Furthermore, PIs are prepared by polycondensation method, precipitated and purified in ethanol solvent, which avoids the use of metal catalysts. The resulting solution-processable devices achieve high performance with a maximum external quantum efficiency (EQE) of 9.94 % and maximum emission peak at 460 nm. To the best of our knowledge, this is the first time that solution-processable polymer light-emitting diodes (PLEDs) based on the "hot exciton" mechanism achieving splendid performance with maximum EQE close to 10 %. The superior performance is attributed to the validity of the "Hinge-type Linking" strategy in PLEDs, opening up a new avenue for PLED development and application. [ABSTRACT FROM AUTHOR]

According to Kasha's rule, high-lying excited states usually have little effect on fluorescence. However, in some molecular systems, the high-lying excited states partly or even mainly contribute to the photophysical properties, especially in the process of harvesting triplet excitons in organic electroluminescent devices. In the current review, we focus on a type of organic light-emitting diode (OLED) materials called "hot exciton" materials, which can effectively harness the non-radiative triplet excitons via reverse intersystem crossing (RISC) from high-lying triplet states to singlet states (Tn → Sm; n ≥ 2, m ≥ 1). Since Ma and Yang proposed the hot exciton mechanism for OLED material design in 2012, there have been many reports aiming at the design and synthesis of novel hot exciton luminogens. Herein, we present a comprehensive review of the recent progress in hot exciton materials. The developments of the hot exciton mechanism are reviewed, the fundamental principles regarding molecular design are discussed, and representative reported hot exciton luminogens are summarized and analyzed, along with their structure–property relationships and OLED applications. [ABSTRACT FROM AUTHOR]

We obtained two high-quality lamellar crystals of cayno-substituted p-phenylene vinylene derivatives and fabricated their transistors. The transistors demonstrated hysteresis-free, low subthreshold swing values of 0.15 and 0.10 V dec−1, and high mobilities of 0.56 and 2.73 cm2 V−1 s−1, respectively. More importantly, the low defect density of 1 per 9.22 × 103 and 1.82 × 104 molecules, respectively, confirmed their high crystal quality. [ABSTRACT FROM AUTHOR]

A novel bipolar compound triphenylamine-dibenzothiophene S,S-dioxide (TPAFSO) based on a dibenzothiophene-S,S-dioxide (DBTO) moiety and a triphenylamine (TPA) unit, in which the TPA unit is linked at its 4-position to the DBTO group at its 3,7-position, is designed and synthesized. The experimental results clearly show that TPAFSO exhibits a high photoluminescence efficiency of 0.52 in a film form and good/balanced carrier injecting properties, as well as an adequate triplet energy (ET) of 2.1 eV to sensitize red phosphor. Hence, solution-processable single-layer green OLEDs using TPAFSO as emitters exhibit a maximum luminous efficiency (LE) of 4.7 cd A−1 and a maximum brightness of 5952 cd m−2 with a low turn-on voltage of 2.5 V, which is superior to the performance of double-layer devices. Furthermore, considering the TPAFSO as a solution-processed host for red emitters, 5% bis(2-(2′-benzothienyl)-pyridinato-N,C3′)iridium(acetylacetonate) (Ir(btp)2(acac))-doped single-layer devices give a maximum quantum yield of 3.9% and a saturated red emission with CIE coordinates of (0.68, 0.32), which are much better than that of Ir(btp)2(acac)-doped poly(N-vinylcarbazole)-2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PVK-PBD) single-layer devices. Additionally, the red OLEDs using 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4Hpyran (DCJTB)-doped TPAFSO as the emitting layer exhibit a maximum LE of 1.8 cd A−1, and can be compared to the performances of DCJTB/Alq3-based multilayer devices via an evaporation process. [ABSTRACT FROM AUTHOR]

Abstract: Herein, a simple aza‐aromatic compound dibenzo[a,c]phenazine (DPPZ), which exhibits single‐molecule white light with a ternary emission, consisting of simultaneous fluorescence (S1→S0) and dual room‐temperature phosphorescence (RTP, T2→S0 and T1→S0) is reported. The Commission Internationale de l' Éclairage coordinates of DPPZ powder are (0.28, 0.33). To everyone's knowledge, this is the first case to achieve single‐molecule white emission with ternary emission of fluorescence and dual RTP. This finding provides a prototype strategy to realize low‐cost, stable pure organic single‐molecule white light emission with three standard primary colors through further precise modulation of excited states. [ABSTRACT FROM AUTHOR]

Ion-doped states are significant for improving the performance in organic semiconductor-based devices, which require clear characterization to understand their relationship with conductivity and charge transporting mechanisms. In this paper, Raman spectroscopy is used to track the evolution of a dianion-anion-neutral mixture in a perylene bisimide (PBI)-doped film under air, with z-scanning carried out in the confocal mode. The precise distribution for the different states along the film depth is realized within 3.5 μm. The whole film is clearly divided into three regions: the ion-poor state, transition region and ion-rich state. The ion ratio and distribution are strongly related to the film conductivity and the onset voltage shift. Changes in the distribution of the ionic species during oxidation and electrode catalysis are clearly recorded by z-scanning, which is beneficial for understanding the charge transfer properties as well as the mechanism underlying working devices. [ABSTRACT FROM AUTHOR]