Collaborative Passivation for Dual Charge Transporting Layers Based on 4-(chloromethyl)benzonitrile Additive toward Efficient and Stable Inverted Perovskite Solar Cells

Poor carrier transport capacity and numerous surface defects of charge transporting layers (CTLs), coupled with misalignment of energy levels between perovskites and CTLs, impact photoelectric conversion efficiency (PCE) of inverted perovskite solar cells (PSCs) profoundly. Herein, a collaborative passivation strategy is proposed based on 4-(chloromethyl) benzonitrile (CBN) as a solution additive for fabrication of both [6,6]-phenyl-C61-butyric acid methylester (PCBM) and poly(triarylamine) (PTAA) CTLs. This additive can improve wettability of PTAA and reduce the agglomeration of PCBM particles, which enhance the PCE and device stability of the PSCs. As a result, a PCE exceeding 20% with a remarkable short circuit current of 23.9 mA cm⁻², and an improved fill factor of 81% is obtained for the CBN- modified inverted PSCs. Devices maintain 80% and 70% of the initial PCE after storage under 30% and 85% humidity ambient conditions for 1000 h without encapsulation, as well as negligible light state PCE loss. This strategy demonstrates feasibility of the additive engineering to improve interfacial contact between the CTLs and perovskites for fabrication of efficient and stable inverted PSCs.     

Conjugated Polyelectrolytes as Multifunctional Passivating and Hole‐Transporting Layers for Efficient Perovskite Light‐Emitting Diodes

Metal halide perovskites (MHPs) have attracted significant attention as light‐emitting materials owing to their high color purities and tunabilities. A key issue in perovskite light‐emitting diodes (PeLEDs) is the fabrication of an optimal charge transport layer (CTL), which has desirable energy levels for efficient charge injection while blocking opposite charges and enabling perovskite layer growth with reduced interfacial defects. Herein, two poly(fluorene‐phenylene)‐based anionic conjugated polyelectrolytes (CPEs) with different counterions (K⁺ and tetramethylammonium (TMA⁺)) are presented as multifunctional passivating and hole‐transporting layers (HTLs). The crystal growth of MHPs grown on different HTLs is investigated through X‐ray photoelectron spectroscopy, X‐ray diffraction, and density functional theory calculation. The CPE bearing the TMA⁺ counterions remarkably improves the growth of perovskites with suppressed interfacial defects, leading to significantly enhanced emission properties and device performance. The luminescent properties are further enhanced via aging and electrical stress application with effective rearrangement of the counterions on the interfacial defects in the perovskites. Finally, efficient formamidinium lead tribromide‐based quasi‐2D PeLEDs with an external quantum efficiency of 10.2% are fabricated. Using CPEs with varying counterions as a CTL can serve as an effective method for controlling the interfacial defects and improving perovskite‐based optoelectronic device properties.     

Transparent Hole-Transporting Frameworks: A Unique Strategy to Design High-Performance Semitransparent Organic Photovoltaics

Thanks to the nature of molecular orbitals, the absorption spectra of organic semiconductors are not continuous like those in traditional inorganic semiconductors, which offers a unique application of organic photovoltaics (OPVs): semitransparent OPVs. Recently, the exciting progress of materials design has promoted the development of semitransparent OPVs. However, in the perspective of device engineering, almost all reported works reduce the thickness of back/reflected electrode to obtain high average visible transmittance (AVT), which is a trade-off between power conversion efficiency (PCE) and the transmittance of the whole solar spectrum (visible and infrared), and therefore limit the further development. Herein, a unique strategy of “transparent hole-transporting frameworks” is proposed. A hole-transporting large-bandgap polymer (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA)) is employed to partially replace polymer donors in the active layer of PBDB-T/Y1. PTAA is a p-type polymer with a large bandgap of 2.9 eV; the partial substitution of PBDB-T by PTAA reduces the absorption of the active layer only in the visible region, keeping the hole-transporting pathways as well as the optimized film morphology. As a result, semitransparent OPVs with PCEs of 12% and AVTs of 20% are achieved, both on rigid and flexible substrates. To demonstrate the generality, this strategy is also used in three different active layers.     

Suppressing Defects-Induced Nonradiative Recombination for Efficient Perovskite Solar Cells through Green Antisolvent Engineering

Organic–inorganic hybrid perovskites have attracted considerable attention due to their superior optoelectronic properties. Traditional one-step solution-processed perovskites often suffer from defects-induced nonradiative recombination, which significantly hinders the improvement of device performance. Herein, treatment with green antisolvents for achieving high-quality perovskite films is reported. Compared to defects-filled ones, perovskite films by antisolvent treatment using methylamine bromide (MABr) in ethanol (MABr-Eth) not only enhances the resultant perovskite crystallinity with large grain size, but also passivates the surface defects. In this case, the engineering of MABr-Eth-treated perovskites suppressing defects-induced nonradiative recombination in perovskite solar cells (PSCs) is demonstrated. As a result, the fabricated inverted planar heterojunction device of ITO/PTAA/Cs_0.15FA_0.85PbI₃/PC₆₁BM/Phen-NADPO/Ag exhibits the best power conversion efficiency of 21.53%. Furthermore, the corresponding PSCs possess a better storage and light-soaking stability.     

Heavy metallic oxide nanoparticles for enhanced sensitivity in semiconducting polymer x-ray detectors

Semiconducting polymers have previously been used as the transduction material in x-ray dosimeters, but these devices have a rather low detection sensitivity because of the low x-ray attenuation efficiency of the organic active layer. Here, we demonstrate a way to overcome this limitation through the introduction of high density nanoparticles having a high atomic number (Z) to increase the x-ray attenuation. Specifically, bismuth oxide (Bi(2)O(3)) nanoparticles (Z?=?83 for Bi) are added to a poly(triarylamine) (PTAA) semiconducting polymer in the active layer of an x-ray detector. Scanning electron microscopy (SEM) reveals that the Bi(2)O(3) nanoparticles are reasonably distributed in the PTAA active layer. The reverse bias dc current-voltage characteristics for PTAA-Bi(2)O(3) diodes (with indium tin oxide (ITO) and Al contacts) have similar leakage currents to ITO/PTAA/Al diodes. Upon irradiation with 17.5?keV x-ray beams, a PTAA device containing 60?wt% Bi(2)O(3) nanoparticles demonstrates a sensitivity increase of approximately 2.5 times compared to the plain PTAA sensor. These results indicate that the addition of high-Z nanoparticles improves the performance of the dosimeters by increasing the x-ray stopping power of the active volume of the diode. Because the Bi(2)O(3) has a high density, it can be used very efficiently, achieving a high weight fraction with a low volume fraction of nanoparticles. The mechanical flexibility of the polymer is not sacrificed when the inorganic nanoparticles are incorporated.     

Fabrication and elimination of PTAA/P4VP layer-by-layer films

Layer-by-layer (LBL) ultra-thin films have been assembled by alternate adsorption of poly(3-thiophene acetic acid) (PTAA) and poly(4-vinyl-pyridine) (P4VP) on planar quartz slides via hydrogen-bonding interaction. Subsequently, the multilayers can be controllably removed by changing the pH values of the aqueous solutions used for film immersion. Our present study is an attempt to reveal the mechanisms of the multilayer film with two-dimensional (2D) ultraviolet-visible (UV-vis) correlation spectroscopy. UV-vis spectroscopy is primarily employed here to monitor the buildup and removal of the ultra-thin films. 2D correlation analysis is performed on the basis of the corresponding spectra for further studies. The morphology of the multilayer film is characterized by atomic force microscopy (AFM). When eliminated in alkaline and acidic aqueous solutions, the polymers in the films show diverse phenomena mainly due to the different extents of dissociation of PTAA and protonation of P4VP at different pH values. In alkaline solution, the elimination of PTAA takes place before P4VP, while in acid solution, the removal of these two polymers adopts a reverse order.     

Multifunctional Resonance Bridge-Mediated Dynamic Modulation of Perovskite Films For Enhanced Intrinsic Stability of Photovoltaics

The improving intrinsic stability, determining the life span of devices, is a challenging task in the industrialization of inverted perovskite solar cells. The most important prerequisite for boosting intrinsic stability is high-quality perovskite films deposition. Here, a molecule, N-(2-pyridyl)pivalamide (NPP) is utilized, as a multifunctional resonance bridge between poly(triarylamine) (PTAA) and perovskite film to regulate the perovskite film quality and promote hole extraction for enhancing the device intrinsic stability. The pyridine groups in NPP couple with the phenyl groups in PTAA through π−π stacking to improve hole extraction capacities and minimize interfacial charge recombination, and the resonance linkages (N CO) in NPP dynamically modulate the perovskite buried defects through strong Pb O bonds based on the fast self-adaptive tautomerization between resonance forms (N CO and N⁺C O⁻). Because of the combined effect of the reduction defect density and improved energy level in the perovskite buried interfaces as well as the optimized crystal orientation in perovskite film enabled by the NPP substrate, the devices based on NPP-grown perovskite films show an efficiency approaching 20% with negligible hysteresis. More impressively, the unencapsulated device displays start-of-the-art intrinsic photostability, operating under continuous 1-sun illumination for 2373 h at 65 °C without loss of PCE.     

Polymer binder effects on the electrical characteristics of 6, 13-bis(triisopropylsilylethynyl)-pentacene thin-film transistors in different solvents

This paper presents the effects of the polymer binder on the electrical properties of 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene) organic thin-film transistors (OTFTs) which have been fabricated using a variety of 2 wt.% TIPS-pentacene solutions that have been prepared in different solutions, including anisole, toluene, and chlorobenzene. Poly(triarylamine) (PTAA) is added as a polymer binder to help the TIPS-pentacene form a stronger binding, thus improving device performances. By using these materials as the active channel, a molecular guest-host system is formed, with TIPS-pentacene as the host and the PTAA as the guest. Introducing the TIPS-pentacene solutions means that the polymer binder and the solvent dependent electrical characteristics can be investigated to determine if the device exhibits the best performance when the solution is prepared with anisole as the solvent and PTAA as the polymer binder. Consequently, a device made from anisole with PTAA exhibits superior electrical properties in comparison to the devices made with the other solutions including the saturation field-effect mobility (μ_sat) ?of 0.21 cm²/V?s, current on/off ratios of 5 × 10⁶, and a sub-threshold slope (SS) of 0.46 V/dec at a gate bias V_GS = -40 V.     

Influence of Ni Interlayers on the Mechanical Properties of Ti6Al4V/(WC-Co) Friction Welds

Ni interlayers were introduced prior to dissimilar friction welding of Ti6Al4V base material to three cemented carbide substrates. The fracture strength of Ti6Al4V/(WC-6 wt% Co) welds were poor and were markedly improved when 20-µm thick Ni interlayers were introduced prior to dissimilar friction welding. These results were only produced when the (WC-6 wt% Co) cermet was electroplated prior to friction welding. When the Ti6Al4V alloy was electroplated prior to friction welding, fractured WC particles and cracking were observed in the (WC-Co) carbide substrate. The fracture strengths of Ti6Al4V/(WC-11 wt% Co) and Ti6Al4V/(WC-24 wt% Co) welds were not improved when 20-µm thick Ni interlayers were introduced prior to friction welding. During mechanical testing, the Ni layer retained at the dissimilar joint interface created a region of weakness.     

Surface modified NiOx as an efficient hole transport layer in inverted perovskite solar cells

Hole transporting materials play a vital role in improving the performance of perovskite solar cells (PSCs). In this work, different concentrations of poly[bis(4-phenyl)(2, 4, 6-trimethylphenyl)amine] (PTAA) are used to modify the surface of sputtered nickel oxide (NiO_x) as hole transport layer (HTL) in inverted PSCs. After the introduction of PTAA, the roughness of the sputtered NiO_x films decreases, while the crystallinity of the perovskite layer increases. The carrier transport across the interface between the sputtered NiO_x film and the perovskite layer is significantly improved. A power conversion efficiency of 18.5% is achieved based on PTAA-modified sputtered NiO_x, exhibiting a 15.2% improvement compared to its pristine counterpart.

     

A Flexible Ionic Liquid Gelled PVA‐Li2SO4 Polymer Electrolyte for Semi‐Solid‐State Supercapacitors

A novel high‐performance flexible gel polymer electrolyte (FGPE) for supercapacitors is prepared by a freeze‐drying method. In the presence of 1‐butyl‐3‐methylimidazolium chloride (BMIMCl) ionic liquid, Li₂SO₄ can easily be added into poly(vinyl alcohol) (PVA) aqueous solution over a large concentration range. The resultant FGPE demonstrates considerably high ionic conductivity (37 mS cm⁻¹) and a high fracture strain at 100% elongation at the optimal weight ratio of PVA:BMIMCl:Li₂SO₄ = 1:3:2.2. The supercapacitor fabricated with the resultant FGPE and activated carbon electrodes shows an electrode‐specific capacitance of 136 F g⁻¹ with a stable operating voltage of 1.5 V, a maximum energy density of 10.6 Wh kg⁻¹, and a power density of 3400 W kg⁻¹. Double supercapacitors in series can efficiently drive a light emitting diode (LED) bulb for over 5 min and the retention of the specific capacitance reaches 90% even after 3000 charge–discharge cycles. The ionic conductivity and charge–discharge behaviors of the resultant FGPE are not affected by bending up to 180°. The flexible supercapacitor device shows only a small capacitance loss of 18% after 1000 cycles of 135° bending.     

Modifying PTAA/Perovskite Interface via 4-Butanediol Ammonium Bromide for Efficient and Stable Inverted Perovskite Solar Cells

Inverted perovskite solar cells (IPSCs) have witnessed an impressive development in recent years. However, their efficiency is still significantly behind theoretical limits, and device instabilities hinder their commercialization. Two main obstacles to further enhancing their performance via one-step deposition are: 1) the unsatisfactory film quality of perovskite and 2) the poor surface contact. To address the above issues, 4-butanediol ammonium Bromide (BD) is utilized to passivate Pb²⁺ defects by forming Pb N bonds and fill vacancies of formamidinium ions at the buried surface of perovskite. The wettability of poly [bis (4-phenyl) (2,4,6-triMethylphenyl) amine] films is also improved due to the formation of hydrogen bonds between PTAA and BD molecules, resulting in better surface contacts and enhanced perovskite crystallinity. As a result, BD-modified perovskite thin films show a significant increase in the mean grain size, as well as a dramatic enhancement in the PL decay lifetime. The BD-treated device exhibits an efficiency of up to 21.26%, considerably higher than the control device. Moreover, the modified devices show dramatically enhanced thermal and ambient stability compared to the control ones. This methodology paves the way to obtain high-quality perovskite films for fabricating high-performance IPSCs.     

Diffusion Bonding of Ti-6Al-4V to QAl 10-3-1.5 with Ni/Cu Interlayers

Ti-6Al-4V and QAl 10-3-1.5 diffusion bonding has been carried out with Ni/Cu interlayers. The diffusion-bonded joints are evaluated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and microhardness test. Intermetallic compounds at the interface zone are detected by X-ray diffraction (XRD). Interfacial microstructure of TiNi+CuTis+α-Ti forms at the Ni/Ti-6Al-4V transition zone and Cu (ss. Ni) solid solution forms between Ni/Cu interlayers. The thickness of reaction layer (TiNi) increases with bonding time by a parabolic law: y2=K0exp(-150000/RT)t, and K0=2.9×10~7 m2/s is figured out from the experiment data.     

Synthesis and characterization of new dithienosilole-based copolymers for polymer solar cells

A series of dithienosilole-based copolymers, poly [(4,4'-bis(2-hexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-5,5'-diyl] (P1), poly[(4,4'-bis(2-hexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,2'-bithiazole)-5,5'-diyl] (P2), poly[(4,4'-bis(2-hexyl)dithieno[3,2-b:2',3'-d]silole)-2, 6-diyl-alt-(10 -methyl-phenothiazine)-3,7-diyl](P3), poly[(4,4'-bis(2-hexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(4,7-bis(2-thienyl)-9,10-anthracene)-5,5'-diyl] (P4) were synthesized by the Pd-catalyzed Stille polymerization method. Electron-deficient benzothiadiazole and bithiazole units and electron-rich phenothiazine and anthracene moieties were incorporated into the polymer backbone to obtain the broad absorption spectrum and to improve the hole-transporting characteristics, respectively. The polymer solar cell (PSC) was fabricated with a layered structure of ITO/PEDOT:PSS/polymer:C71-PCBM (1:3)/LiF/Al. The best performance of PSC was obtained at P3:C71-PCBM which reaches a power conversion efficiency (PCE) of 1.18%, with a short circuit current density (J(sc)) of 4.75 mA/cm2, an open circuit voltage (V(oc)) of 0.71 V, and a fill factor (FF) of 0.35 under AM 1.5G irradiation (100 mW/cm2).     

Cationic phenylene ethynylene polymers and oligomers exhibit efficient antiviral activity

The antiviral activities of poly(phenylene ethynylene) (PPE)-based cationic conjugated polyelectrolytes (CPE) and oligo-phenylene ethynylenes (OPE) were investigated using two model viruses, the T4 and MS2 bacteriophages. Under UV/visible light irradiation, significant antiviral activity was observed for all of the CPEs and OPEs; without irradiation, most of these compounds exhibited high inactivation activity against the MS2 phage and moderate inactivation ability against the T4 phage. Transmission electron microscopy (TEM) and SDS polyacrylamide gel electrophoresis (SDS-PAGE) reveal that the CPEs and OPEs exert their antiviral activity by partial disassembly of the phage particle structure in the dark and photochemical damage of the phage capsid protein under UV/visible light irradiation.     

Critical Role of Interface and Crystallinity on the Performance and Photostability of Perovskite Solar Cell on Nickel Oxide

Hybrid perovskites are on a trajectory toward realizing the most efficient single‐junction, solution‐processed photovoltaic devices. However, a critical issue is the limited understanding of the correlation between the degree of crystallinity and the emergent perovskite/hole (or electron) transport layer on device performance and photostability. Here, the controlled growth of hybrid perovskites on nickel oxide (NiO) is shown, resulting in the formation of thin films with enhanced crystallinity with characteristic peak width and splitting reminiscent of the tetragonal phase in single crystals. Photophysical and interface sensitive measurements reveal a reduced trap density at the perovskite/NiO interface in comparison with perovskites grown on poly(3,4‐ethylene dioxy thiophene) polystyrene sulfonate. Photovoltaic cells exhibit a high open circuit voltage (1.12 V), indicating a near‐ideal energy band alignment. Moreover, photostability of photovoltaic devices up to 10‐Suns is observed, which is a direct result of the superior crystallinity of perovskite thin films on NiO. These results elucidate the critical role of the quality of the perovskite/hole transport layer interface in rendering high‐performance and photostable optoelectronic devices.     

Small Molecules Functionalized Zinc Oxide Interlayers for High Performance Low-Temperature Carbon-Based CsPbI2Br Perovskite Solar Cells

The charge recombination resulting from bulk defects and interfacial energy level mismatch hinders the improvement of the power conversion efficiency (PCE) and stability of carbon-based inorganic perovskite solar cells (C-IPSCs). Herein, a series of small molecules including ethylenediaminetetraacetic acid (EDTA) and its derivatives (EDTA-Na and EDTA-K) are studied to functionalize the zinc oxide (ZnO) interlayers at the SnO₂/CsPbI₂Br buried interface to boost the photovoltaic performance of low-temperature C-IPSCs. This strategy can simultaneously passivate defects in ZnO and perovskite films, adjust interfacial energy level alignment, and release interfacial tensile stress, thereby improving interfacial contact, inhibiting ion migration, alleviating charge recombination, and promoting electron transport. As a result, a maximum PCE of 13.94% with a negligible hysteresis effect is obtained, which is one of the best results reported for low-temperature CsPbI₂Br C-IPSCs so far. Moreover, the optimized devices without encapsulation demonstrate greatly improved operational stability.     

Alignment of a conjugated polymer onto amyloid-like protein fibrils

The amyloid-like fibril is a biomolecular nanowire template of very high stability. Here we describe the coordination of a conjugated polyelectrolyte, poly(thiophene acetic acid) (PTAA), to bovine insulin fibrils with widths of <10 nm and lengths of up to more than 10 microm. Fibrils complexed with PTAA are aligned on surfaces through molecular combing and transfer printing. Single-molecule spectroscopy techniques are applied to chart spectral variation in the emission of these wires. When these results are combined with analysis of the polarization of the emitted light, we can conclude that the polymer chains are preferentially aligned along the fibrillar axis.     

Interaction of 2,4,6-trichlorophenol with high carbon iron filings: Reaction and sorption mechanisms

Reductive dehalogenation of 2,4,6-trichlorophenol (2,4,6-TCP) by two types of high carbon iron filings (HCIF), HCIF-1 and HCIF-2 was studied in batch reactors. While the iron, copper, manganese and carbon content of the two types of HCIF was similar, the specific surface area of HCIF-1 and HCIF-2 were 1.944 and 3.418m(2)g(-1), respectively. During interaction with HCIF-1, 2,4,6-TCP adsorbed on HCIF-1 surface resulting in rapid reduction of aqueous phase 2,4,6-TCP concentration. However, reductive dehalogenation of 2,4,6-TCP was negligible. During interaction between 2,4,6-TCP and HCIF-2, both 2,4,6-TCP adsorption on HCIF-2, and 2,4,6,-TCP dechlorination was observed. 2,4,6-TCP partitioning between solid and aqueous phase could be described by a Freundlich isotherm, while 2,4,6-TCP dechlorination could be described by an appropriate rate expression. A mathematical model was developed for describing the overall interaction of 2,4,6-TCP with HCIF-2, incorporating simultaneous adsorption/desorption and dechlorination reactions of 2,4,6-TCP with the HCIF surface. 2,4-Dichlorophenol (2,4-DCP), 2-chlorophenol (2-CP) and minor amounts of 4-chlorophenol (4-CP) evolved as 2,4,6-TCP dechlorination by-products. The evolved 2,4-DCP partitioned strongly to the HCIF surface. 4-CP and 2-CP accumulated in the aqueous phase. No transformation of 2-CP or 4-CP to phenol was observed.     

原位交联凝胶聚合物电解质的制备及性能

采用相转化法制备了聚偏氟乙烯(PVDF)和苯乙烯-氧化乙烯-苯乙烯三嵌段共聚物(PS-PEO-PS)的共混多孔前体膜,再利用芳香官能团的傅克反应将前体膜原位交联,交联膜吸收电解液后得到交联凝胶聚合物电解质(CPEs)。对交联膜的形貌、热稳定性以及CPEs的电化学性能进行了表征,探讨了嵌段共聚物中PEO的链段长度对CPEs综合性能的影响。结果表明,CPEs交联膜的孔隙率和热稳定性较纯PVDF膜有很大的提升,其中CPE-2交联膜的孔隙率最高为72.3%,300℃时仍能保持稳定的孔隙结构,且几乎没有尺寸收缩,测试用半电池室温下显示出高的离子电导率(2.09mS/cm)和良好的充放电性能。