Amino N‐Oxide Functionalized Conjugated Polymers and their Amino‐Functionalized Precursors: New Cathode Interlayers for High‐Performance Optoelectronic Devices

A series of amino N‐oxide functionalized polyfluorene homopolymers and copolymers (PNOs) are synthesized by oxidizing their amino functionalized precursor polymers (PNs) with hydrogen peroxide. Excellent solubility in polar solvents and good electron injection from high work‐function metals make PNOs good candidates for interfacial modification of solution processed multilayer polymer light‐emitting diodes (PLEDs) and polymer solar cells (PSCs). Both PNOs and PNs are used as cathode interlayers in PLEDs and PSCs. It is found that the resulting devices show much better performance than devices based on a bare Al cathode. The effect of side chain and main chain variations on the device performance is investigated. PNOs/Al cathode devices exhibit better performance than PNs/Al cathode devices. Moreover, devices incorporating polymers with para‐linkage of pyridinyl moieties exhibit better performance than those using polymers with meta‐linked counterparts. With a poly[(2,7‐(9,9‐bis(6‐(N,N‐diethylamino)‐hexyl N‐oxide)fluorene))‐alt‐(2,5‐pyridinyl)] (PF6NO25Py) cathode interlayer, the resulting device exhibits a luminance efficiency of 16.9 cd A^?1 and a power conversion efficiency of 6.9% for PLEDs and PSCs, respectively. These results indicate that PNOs are promising new cathode interlayers for modifying a range of optoelectronic devices.     

Unexpected Propeller‐Like Hexakis(fluoren‐2‐yl)benzene Cores for Six‐Arm Star‐Shaped Oligofluorenes: Highly Efficient Deep‐Blue Fluorescent Emitters and Good Hole‐Transporting Materials

Grafting six fluorene units to a benzene ring generates a new highly twisted core of hexakis(fluoren‐2‐yl)benzene. Based on the new core, six‐arm star‐shaped oligofluorenes from the first generation T1 to third generation T3 are constructed. Their thermal, photophysical, and electrochemical properties are studied, and the relationship between the structures and properties is discussed. Simple double‐layer electroluminescence (EL) devices using T1–T3 as non‐doped solution‐processed emitters display deep‐blue emissions with Commission Internationale de l'Eclairage (CIE) coordinates of (0.17, 0.08) for T1 , (0.16, 0.08) for T2 , and (0.16, 0.07) for T3 . These devices exhibit excellent performance, with maximum current efficiency of up to 5.4 cd A^?1, and maximum external quantum efficiency of up to 6.8%, which is the highest efficiency for non‐doped solution‐processed deep‐blue organic light‐emitting diodes (OLEDs) based on starburst oligofluorenes, and is even comparable with other solution‐processed deep‐blue fluorescent OLEDs. Furthermore, T2‐ and T3‐ based devices show striking blue EL color stability independent of driving voltage. In addition, using T0–T3 as hole‐transporting materials, the devices of indium tin oxide (ITO)/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS)/ T0–T3 /tris(8‐hydroxyquinolinato)aluminium (Alq₃)/LiF/Al achieve maximum current efficiencies of 5.51–6.62 cd A^?1, which are among the highest for hole‐transporting materials in identical device structure.     

Zwitterionic ammonium and neutral amino molecules as cathode interlayer for inverted polymer solar cells

Cathode interlayer is essential to inverted bulk heterojunction polymer solar cells (PSCs). A series of zwitterionic ammonium and neutral amino organic molecules are introduced into inverted PSCs as cathode interlayer and power conversion efficiency (PCE) as high as 8.07% is demonstrated. Compared to the devices without interlayer, all the devices exhibit significant improvements of the device parameters by reducing the work function of indium tin oxide (ITO) cathode. It is striking that the devices with neutral amino molecules as interlayer exhibit remarkably higher PCEs than the devices with zwitterionic ammonium molecules as interlayer. We attribute the improved performance to the better photoactive morphology induced by the hydrophobic properties of the neutral amino derivatives through research of ultraviolet photoelectron spectroscopy, atomic force microscopy, and contact angle measurements. Interestingly, the PCEs of the inverted PSCs with cathode interlayer are positively correlated with the hydrophobic properties of the interlayer materials, since devices with neutral amino molecules or molecules with a more hydrophobic alkyl pendant (piperidine) as interlayer exhibit higher PCEs. These results pave the way to the design of effective cathode interlayer materials.     

Tuning Contact Resistance in Top‐Contact p‐Type and n‐Type Organic Field Effect Transistors by Self‐Generated Interlayers

Contact resistance significantly limits the performance of organic field‐effect transistors (OFETs). Positioning interlayers at the metal/organic interface can tune the effective work‐function and reduce contact resistance. Myriad techniques offer interlayer processing onto the metal pads in bottom‐contact OFETs. However, most methods are not suitable for deposition on organic films and incompatible with top‐contact OFET architectures. Here, a simple and versatile methodology is demonstrated for interlayer processing in both p‐ and n‐type devices that is also suitable for top‐contact OFETs. In this approach, judiciously selected interlayer molecules are co‐deposited as additives in the semiconducting polymer active layer. During top contact deposition, the additive molecules migrate from within the bulk film to the organic/metal interface due to additive‐metal interactions. Migration continues until a thin continuous interlayer is completed. Formation of the interlayer is confirmed by X‐ray photoelectron spectroscopy (XPS) and cross‐section scanning transmission electron microscopy (STEM), and its effect on contact resistance by device measurements and transfer line method (TLM) analysis. It is shown that self‐generated interlayers that reduce contact resistance in p‐type devices, increase that of n‐type devices, and vice versa, confirming the role of additives as interlayer materials that modulate the effective work‐function of the organic/metal interface.     

Organic donor-σ-acceptor molecules based on 1,2,4,5-tetrakis((E)-2-(5′-hexyl-2,2′-bithiophen-5-yl)vinyl)benzene and perylene diimide derivative and their application to photovoltaic devices

Donor-σ-acceptor molecules of HPBT-n(PDI) (n = 1, 2, and 4) containing perylene diimide (PDI) and π-extended 1,2,4,5-tetrakis((E)-2-(5′-hexyl-2,2′-bithiophen-5-yl)vinyl)benzene (HPBT) have been successfully synthesized for studying the self-organization of each moiety and their applications in photovoltaic devices. Interesting features were found in these molecules: the aggregation-induced crystallization in the HPBT moieties enhanced the power conversion efficiency (PCE) in the photovoltaic cell. By incorporating HPBT as the donor and PDI as the acceptor moiety, we anticipated that their high degree of independent aggregation-induced crystallization would yield electron/hole transport channels and high mobility in the desired direction of charge transport. In a photovoltaic device, HPBT-1(PDI) gave a PCE of 0.22% with an open circuit voltage ranging from 0.62 to 0.63 V. When the HPBT moiety was more hindered by the PDI moiety, less PCE was observed in HPBT-2(PDI). Addition of methanofullerene [6,6]-phenyl C61-butyric acid methyl ester (PCBM) resulted in enhancement of the PCE due to enhanced visible absorption. The device bearing HPBT-1(PDI) and PCBM (1:4 mol ratio) demonstrate much higher PCE to be around 1.60%.     

不同插入层对抑制Mg掺杂p-GaN的记忆效应

研究了低温(LT) GaN和AlN不同插入层对抑制Mg掺杂p-GaN金属有机化学气相沉积外延中存在的记忆效应的影响,外延生长p-GaN缓冲层,制作具有该缓冲层的AlGaN/GaN高电子迁移率晶体管(HEMT),并对该器件进行电学测试.二次离子质谱仪测试表明p-GaN上10 nm厚的LT-GaN插入层相比于2 nm厚的AlN插入层能更好地抑制Mg扩散.霍尔测试表明,2 nm厚的AlN插入层的引入和GaN存在较大的晶格失配会引入位错,进而会降低AlGaN/GaNHEMT的电子迁移率以及增加其方块电阻;含有10 nm厚的LT-GaN插入层的p-GaN作为缓冲层的AlGaN/GaN HEMT,其方块电阻、电子迁移率以及二维电子气(2DEG)密度分别为334.9 Ω/口,1 923 cm2/(V·s)和9.68×1012 cm-2.器件具有很好的直流特性,其饱和电流为470 mA/mm,峰值跨导为57.7 mS/mm,电流开关比为3.13×109.     

Multi‐channel interface dipole of hyperbranched polymers with quasi‐immovable hydrion to modification of cathode interface for high‐efficiency polymer solar cells

The single‐junction polymer solar cells (PSCs) with high power conversion efficiency (PCE) are demonstrated by first incorporating two hyperbranched polymers (carboxylic acid functionalized hyperbranched poly(ether ketone) (CHBPEK) and sulfonic acid functionalized hyperbranched poly(ether sulfone) (SHBPES)) with carboxylic and sulfonic acid groups to modify the cathode interface. The effect of cathode modification by CHBPEK or SHBPES for conventional PSCs based on different active‐layer materials is systematically investigated. Compared with traditional LiF/Al, Ca/Al, and PFN/Al devices, significant improvement in short circuit current and fill factors are achieved by employing CHBPEK or SHBPES. In particular, the device with SHBPES as cathode interlayer can be achieved with a highest PCE of 9.12%, which are among the high performance reported for single‐junction PSCs modified with hyperbranched interlayers. Importantly, the influence of the hyperbranched polymer interlayer modification on the cathode interface is also discussed and found to be the formation of the stable multi‐channel interface dipole based on quasi‐immovable counterions in these polymers. The results supply a feasible means to obtain the improved J_SC and FF for high efficiency PSCs. Copyright © 2016 John Wiley & Sons, Ltd.     

不同界面层对HfTaON栅介质MOS特性的影响

采用磁控溅射方法,在Si衬底上制备HfTaON高k栅介质,研究了AlON、HfON、TaON不同界面层对MOS器件电特性的影响。结果表明,HfTaON/AlON叠层栅介质结构由于在AlON界面层附近形成一种Hf-Al-O"熵稳定"的亚稳态结构,且AlON具有较高的结晶温度、与Si接触有好的界面特性等,使制备的MOS器件表现出优良的电性能:低的界面态密度、低的栅极漏电、高的可靠性以及高的等效k值(21.2)。此外,N元素的加入可以抑制Hf和Ta的扩散,有效抑制界面态的产生,并使器件具有优良的抵抗高场应力的能力。     

Fluorene-based cathode interlayer polymers for high performance solution processed organic optoelectronic devices

A hydrophilic polyfluorene-based conjugated polyelectrolyte (CPE) Poly[9,9-bis(4′-(6″-(diethanolamino)hexyloxy) phenyl)fluorene], PPFN-OH (Scheme 1) has been synthesized and utilized as cathode interlayer for both polymer light emitting diodes (PLEDs) and solar cells (PSCs). For comparison, another CPE namely Poly[9,9-bis(6′-(diethanolamino)hexyl)fluorene] (PFN-OH) has also been investigated. They comprise the same polyfluorene backbone structures with, respectively, diethanolaminohexyl (PFN-OH) and diethanolaminohexoxyphenyl (PPFN-OH) substituents attached to the C9 carbon of the fluorene repeat unit. In comparison to reference devices with more reactive Ca/Al cathodes, utilizing these CPEs as interlayers allowed an Al cathode to be used for blue light emission PLEDs, yielding 51% and 92% enhancement of maximum luminous efficiency (LE) for PFN-OH and PPFN-OH, respectively. The PLEDs with PPFN-OH showed both higher maximum LE and maximum luminance (L) (LE = 2.53 cd/A at 6.2 V, L = 9917 cd/m² at 8.3 V) than devices with PFN-OH (2.00 cd/A at 4.1 V, 3237 cd/m² at 7.2 V). The PPFN-OH PLEDs also showed no significant roll-off in efficiency with increasing current density up to 400 mA/cm², indicating excellent electron injection ability and stability for this interlayer. The insertion of alkoxy-phenyl groups at the C9-position in PPFN-OH is clearly advantageous. This simple modification significantly improves the CPE cathode interlayer performance. Parallel investigations of the electron extraction properties of PPFN-OH in inverted architecture PSCs with PCDTBT:PC₇₀BM bulk heterojunction active layers demonstrated a power conversion efficiency enhancement of ∼19% (from 4.99% to 5.95%) for indium tin oxide cathode devices compared with reference devices using Ca/Al cathodes. These results confirm PPFN-OH to be a promising interlayer material for high performance solution processed organic optoelectronic devices.     

Ultrathin MnO2/Graphene Oxide/Carbon Nanotube Interlayer as Efficient Polysulfide‐Trapping Shield for High‐Performance Li–S Batteries

Ultrathin MnO₂/graphene oxide/carbon nanotube (G/M@CNT) interlayers are developed as efficient polysulfide‐trapping shields for high‐performance Li–S batteries. A simple layer‐by‐layer procedure is used to construct a sandwiched vein–membrane interlayer of thickness 2 µm and areal density 0.104 mg cm^?2 by loading MnO₂ nanoparticles and graphene oxide (GO) sheets on superaligned carbon nanotube films. The G/M@CNT interlayer provides a physical shield against both polysulfide shuttling and chemical adsorption of polysulfides by MnO₂ nanoparticles and GO sheets. The synergetic effect of the G/M@CNT interlayer enables the production of Li–S cells with high sulfur loadings (60–80 wt%), a low capacity decay rate (?0.029% per cycle over 2500 cycles at 1 C), high rate performance (747 mA h g^?1 at a charge rate of 10 C), and a low self‐discharge rate with high capacity retention (93.0% after 20 d rest). Electrochemical impedance spectroscopy, cyclic voltammetry, and scanning electron microscopy observations of the Li anodes after cycling confirm the polysulfide‐trapping ability of the G/M@CNT interlayer and show its potential in developing high‐performance Li–S batteries.     

Thin reduced graphene oxide interlayer with a conjugated block copolymer for high performance non-volatile ferroelectric polymer memory

Polymer ferroelectric-gate field effect transistors (Fe-FETs) employing ferroelectric polymer thin films as gate insulators are highly attractive as a next-generation non-volatile memory. For minimizing gate leakage current of a device which arises from electrically defective ferroelectric polymer layer in particular at low operation voltage, the materials design of interlayers between the ferroelectric insulator and gate electrode is essential. Here, we introduce a new solution-processed interlayer of conductive reduced graphene oxides (rGOs) modified with a conjugated block copolymer, poly(styrene-block-paraphenylene) (PS-b-PPP). A FeFET with a solution-processed p-type oligomeric semiconducting channel and ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) insulator exhibited characteristic source–drain current hysteresis arising from ferroelectric polarization switching of a PVDF-TrFE insulator. Our PS-b-PPP modified rGOs (PMrGOs) with conductive moieties embedded in insulating polymer matrix not only significantly reduced the gate leakage current but also efficiently lowered operation voltage of the device. In consequence, the device showed large memory gate voltage window and high ON/OFF source–drain current ratio with excellent data retention and read/write cycle endurance. Furthermore, our PMrGOs interlayers were successfully employed to FeFETs fabricated on mechanically flexible substrates with promising non-volatile memory performance under repetitive bending deformation.     

Fluorinated and non-fluorinated conjugated polymers showing different photovoltaic properties in polymer solar cells with PFNBr interlayers

Photovoltaic properties of the two polymers (named as PBQ-0F and PBQ-4F) were investigated by employing [6, 6]-phenyl-C₇₁-butyric acid methyl ester (PC₇₁BM) as the acceptor and a water-alcohol-soluble polymer interlayer material (named as PFNBr) to fabricate photovoltaic devices. For the PBQ-0F:PC₇₁BM blend, the device using Ca/Al as cathode showed very similar efficiency as the device using PFNBr/Al as cathode, while for the PBQ-0F:PC₇₁BM blend, photovoltaic performance of the device can be distinctly improved by replacing Ca/Al with PFNBr/Al. As a result, the best PCE of the PBQ-4F:PC₇₁BM based devices reached 9.04%, which is much higher than that of the PBQ-0F:PC₇₁BM based devices. The results obtained from the quantum chemistry calculations and water contact angle measurements demonstrate that these two polymers are low polar materials, and also the films based on them have hydrophobic surfaces. Since PFNBr has an amphipathic structure (hydrophobic backbone and hydrophilic side chain) and the blend films of PBQ-4F:PC₇₁BM and PBQ-4F:PC₇₁BM have different surface energies, the PFNBr organization atop these two blend types of should be different, which will affect device photovoltaic performance.     

Optimization of the Power Conversion Efficiency of Room Temperature‐Fabricated Polymer Solar Cells Utilizing Solution Processed Tungsten Oxide and Conjugated Polyelectrolyte as Electrode Interlayer

The utilization of a conjugated polyelectrolyte‐ionic liquid crystal (CPE‐ILC) complex as electron transporting layer (ETL) to improve the compatibility between the ITO and hydrophobic active layer and to promote the dipole orientation at cathode interface is reported. Simultaneously, a hole transporting layer (HTL) of solution processed tungsten oxide together with poly(2,6‐bis(trimethyltin)‐4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′]dithiophene‐alt‐4,6‐Dibromo‐thieno[3,4‐b]thiophene‐2‐carboxylic acid 2‐[2‐(2‐methoxy‐ethoxy)‐ethoxy]‐ethyl ester) (PBDTT‐TT‐TEG) efficiently shifts the work function of Ag electrode in this device. The interfacial modification of these interlayers achieves energy alignment at both electrodes. The power conversion efficiency (PCE) of the PSC based on ITO/PFN‐CbpSO/PBDTTT‐C‐T:PC₇₀BM/PBDTT‐TT‐TEG/WO₃/Ag with solution processed interlayers reaches to 7.8%. It is worthy to note that except for the electrodes, all layers of device are fabricated by solution process at room temperature and without annealing. In the case of incorporating ZnO layer into this device, the device efficiency further increases to 8.5%, which is the best value reported from PBDTTT‐C‐T:PC₇₀BM‐based solar cells with solution processed interlayers at both electrodes so far.     

Achieving Highly Efficient Fluorescent Blue Organic Light‐Emitting Diodes Through Optimizing Molecular Structures and Device Configuration

Based on the results of first‐principles calculations of the electronic properties of blue light‐emitting materials, the molecular structures of oligofluorenes are optimized by incorporating electron‐withdrawing groups into the molecules to balance hole and electron injection and transport for organic light‐emitting diodes (OLEDs). The result is a remarkable improvement in the maximum external quantum efficiency (EQE) of the undoped device from 2.0% to 4.99%. Further optimization of the device configurations and processing procedures, e.g., by changing the thickness of the emitting layer and through thermal annealing treatments, leads to a very high maximum EQE of 7.40% for the undoped sky‐blue device. Finally, by doping the emitter in a suitable host material, 4,4’‐bis(carbazol‐9‐yl)biphenyl (CBP), at the optimal concentration of 6%, pure blue emission with extremely high maximum EQE of 9.40% and Commission Internationale de l’Eclairage (CIE) coordinates of (0.147, 0.139) is achieved.     

Non-interlayer and color stable WOLEDs with mixed host and incorporating a new orange phosphorescent iridium complex

In this work, we have synthesized a new phosphorescent iridium complex (Bppya)₂Ir(acac), as an orange dopant for organic light-emitting diodes (OLEDs). The device achieved an external quantum efficiency (EQE) of 22.4%, a current efficiency of 49.5 cd A⁻¹ and a power efficiency of 38.9 lm W⁻¹, which are among the highest values for orange OLEDs. Furthermore, color stable and high efficiency phosphorescent white OLED (WOLED) was demonstrated by utilizing a mixed-host in the emissive layers (EMLs) composed of a blue phosphor and the new orange phosphorescent emitter, as well as by avoiding the use of interlayers that commonly exist between different EMLs in WOLEDs. Our WOLED presented decent white emission with maximum efficiencies of 25.3 cd A⁻¹ and 12.6%. Furthermore, the 1931 Commission Internationale de l’Eclairage color coordinates exhibited extremely small variation of (0.3940 ± 0.0102, 0.4323 ± 0.0046) in a wide luminance range from 49 to 38,035 cd m⁻² when driving voltages increased from 4 V to 12 V. The root cause for this excellent color stability is the utilization of the mixed-host to obtain bipolar transport properties in EMLs as well as the eliminating of interlayer between different EMLs, which, on one hand, effectively broaden the exciton recombination zone; on the other hand, reduce the accumulation of triplet excitons at the emissive interface.     

中间带宽插入层对InGaN太阳能电池的影响

利用wxAMPS软件对吸收层In组分为0.2的非极性InGaN基P-I-N结构双异质结太阳能电池进行仿真,分别研究了在P-I结和I-N结处插入In_0.1 Ga_0.9N做为中间带宽插入层对太阳能电池效率的影响。通过仿真发现,随着P-I结处插入层厚度增加,太阳能电池效率先增加后减少,而随着I-N结处插入层厚度增加,太阳能电池效率递增,但厚度超过10 nm时,增加速率迅速减小。最后再利用仿真所得的最优数据设计出同时使用两种插入层的新结构电池,共15 nm的中间带宽插入层将电池效率从10.7%提高至11.2%。     

Quinoxaline-Based X-Shaped Sensitizers as Self-Assembled Monolayer for Tin Perovskite Solar cells

Four X-shaped quinoxaline-based organic dyes, PQx (1), TQx, (2), PQxD (3), and TQxD (4) (D = dye sensitizers) are developed and served as p-type self-assemble monolayer (SAM) for tin perovskite solar cells (TPSC). Thermal, optical, and electrochemical properties of these SAMs are thoroughly investigated and characterized. Tin perovskite layers are successfully deposited on these four SAM surfaces according to a two-step approach and the devices exhibit power conversion efficiency in the order of TQxD (8.3%) > TQx (8.0%) > PQxD (7.1%) > PQx (6.1%). With thiophene π-extended conjugation unit in SAM structure, TQxD (4) exhibits the highest hole extraction rates, greatest hole mobilities, and slowest charge recombination to achieve great device performance of 8.3%, which is the current best result for SAM-based TPSC ever reported. Furthermore, all devices except PQx shows great enduring stability for the performance retaining ≈90% of their original values for shelf storage over 1600 h.     

High efficiency blue PhOLEDs using spiro-annulated triphenylamine/fluorene hybrids as host materials with high triplet energy,high HOMO level and high Tg

Two spiro-annulated triphenylamine/fluorene oligomers, namely 4′-(9,9′-spirobifluoren-4-yl)-10-phenyl-10H-spiro[acridine-9,9′-fluorene] (NSF-SF), and 4,4′-di(spiro(triphenylamine-9,9′-fluorene)-2-yl)-spiro(triphenylamine-9,9′-fluorene) (NSF-NSF), are designed and synthesized. Their thermal, electrochemical and photophysical properties were investigated. The introduction of spiro-annulated triphenylamine moieties assurances the high HOMO energy levels of NSF-NSF and NSF-SF at −5.31 eV and −5.33 eV, respectively, which accordingly facilitates the hole injection from nearby hole-transporting layer. Meanwhile, the perpendicular arrangement of the spiro-conformation and the full ortho-linkage effectively prevents the extension of the π-conjugation and consequently guarantees their high triplet energies of 2.83 eV. Phosphorescent organic light-emitting devices (PhOLEDs) with the configurations of ITO/MoO₃/TAPC/EML/TmPyPB/LiF/Al were fabricated by using the two compounds as host materials and bis[2-(4′,6′-difluorophenyl)pyridinato-N,C^2′]iridium(III) picolate (FIrpic) as the dopant. The turn-on voltage of the device B based on NSF-NSF was 2.8 V. Simultaneously, the device exhibited excellent performance with the maximum current efficiency of 41 cd A⁻¹, the maximum power efficiency of 42 lm W⁻¹ and the maximum external quantum efficiency (EQE) of 19.1%. At a high brightness of 1000 cd m⁻², the device remained EQE of 16.2% and the roll-off value of external quantum efficiency is 15%.     

Suppressing Sodium Dendrites by Multifunctional Polyvinylidene Fluoride (PVDF) Interlayers with Nonthrough Pores and High Flux/Affinity of Sodium Ions toward Long Cycle Life Sodium Oxygen‐Batteries

Rechargeable sodium–oxygen (Na–O₂) batteries are of interest due to their high specific capacity, high equilibrium potential output, and the abundance of sodium resources; however, their cycle life is still very poor due to instability of electrolytes and especially the uncontrollable growth of Na dendrites. Herein, as a proof‐of‐concept experiment, a facile and low‐cost strategy is first proposed and demonstrated to effectively suppress growth of Na dendrites by using a fibrillar polyvinylidene fluoride film (f‐PVDF) with nonthrough pore as a multifunctional blocking interlayer. Unexpectedly, the f‐PVDF interlayer endows Na–O₂ battery with superior electrochemical performances, including high rate capability and long cycle life (up to 87 cycles), which is superior to those of the compact PVDF (c‐PVDF), PVDF with through pores (p‐PVDF), polyethylene oxide (PEO), and conventional polytetrafluoroethylene (PTFE) counterparts due to the following combined advantages: (1) the stronger C? F polar function groups provide a better affinity to Na ions, thus enabling a more homogeneous Na deposition than that of C? O function groups in PEO interlayer; (2) compared with c‐PVDF and p‐PVDF interlayers, f‐PVDF holds more electrolyte uptake for higher ion conductivity; (3) the good wettability of the f‐PVDF interlayer with electrolyte benefits Na dendrite suppression compared with PTFE interlayer.     

Stable low-voltage organic memory transistors with poly(vinyl alcohol) layers stabilized by vinyl silicon oxide interlayers

Here we report stable transistor-type organic memory devices (TOMDs) with poly(vinyl alcohol) (PVA) gate-insulating memory layers stabilized by vinyl-silicon oxide (VSiO) interlayers that are formed via sol-gel reaction of vinyl triethoxysilane (VTES). The thickness of the VSiO interlayers, which are placed between the PVA layers and the poly(3-hexylthiophene) (P3HT) channel layers, was varied up to 250 nm. In order to investigate the thermal stability, all devices were thermally treated at 150 °C for 30 min. The transistor performance and hysteresis characteristics were greatly improved for the PVA-TOMDs with the VSiO interlayers after thermal treatment, whereas the PVA-TOMD without the VSiO interlayer was severely degraded after thermal treatment. In particular, the thermally-treated PVA-TOMD with the 80 nm-thick VSiO interlayer exhibited stable low-voltage driving and outstanding retention characteristics with >10,000 cycles upon continuous writing-reading-erasing-reading operation.