Giant Second Harmonic Generation in Supertwisted WS Spirals Grown in Step-Edge Particle-Induced Non-Euclidean Surfaces.

In moiré crystals resulting from the stacking of twisted two-dimensional (2D) layered materials, a subtle adjustment in the twist angle surprisingly gives rise to a wide range of correlated optical and electrical properties. Herein, we report the synthesis of supertwisted WS spirals and the observation of giant second harmonic generation (SHG) in these spirals. Supertwisted WS spirals featuring different twist angles are synthesized on a Euclidean or step-edge particle-induced non-Euclidean surface using carefully designed water-assisted chemical vapor deposition.

SnSe Quantum Dots and Chlorhexidine Acetate Suppress Synergistically Non-radiative Recombination Loss for High Efficiency and Stability Perovskite Solar Cells.

Non-radiative recombination losses limit the property of perovskite solar cells (PSCs). Here, a synergistic strategy of SnSeQDs doping into SnO and chlorhexidine acetate (CA) coating on the surface of perovskite is proposed. The introduction of 2D SnSeQDs reduces the oxygen vacancy defects and increases the carrier mobility of SnO.

Buried Interface Optimization for Flexible Perovskite Solar Cells with High Efficiency and Mechanical Stability.

The power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs) are significantly reduced by defect-induced charge non-radiative recombination. Also, unexpected residual strain in perovskite films leads to an unfavorable impact on the stability and efficiency of PSCs, notably flexible PSCs (f-PSCs). Considering these problems, a thorough and effective strategy is proposed by incorporating phytic acid (PA) into SnO as an electron transport layer (ETL).

Regulating the Crystallization Growth of Sn-Pb Mixed Perovskites Using the 2D Perovskite (4-AMP)PbI Substrate for High-Efficiency and Stable Solar Cells.

Sn-Pb mixed perovskite solar cells (PSCs) are developing rapidly and making great progress due to their environmentally friendly advantages. High-crystalline quality perovskite films are essential for obtaining high-efficiency and -stability PSCs. Here, the DJ-phase two-dimensional (2D) perovskite (4-AMP)PbI (4-AMP is 4-(aminomethyl) piperidine) was used as a substrate to regulate the crystallization growth of the Sn-Pb mixed perovskite for preparing high-quality perovskite films, and the regulation mechanism was analyzed in detail.

2D Perovsktie Substrate-Assisted CsPbI Film Growth for High-Efficiency Solar Cells.

High-quality perovskite films are beneficial for fabricating perovskite solar cells (PSCs) with excellent photoelectric performance. The substrate on which the perovskite film grows plays a profound role in improving the crystallization quality of the perovskite film. Here, we proposed a novel method for optimizing CsPbI perovskite films, that is, two-dimensional (2D) perovskite substrate-assisted growth (2D-PSAG) method.

Multifunction Sandwich Structure Based on Diffusible 2-Chloroethylamine for High-Efficiency and Stable Tin-Lead Mixed Perovskite Solar Cells.

Low-bandgap tin-lead mixed perovskites (PVKs) are necessary for all-perovskite tandem solar cells. This work proposes a multifunctional sandwich structure with 2-chloroethylamine (CEA) as the top and bottom interface layer and perovskite as the core layer. The sandwich structured CEA allows large ClCHCHNH and small Cl to diffuse into the crystal lattice and grain boundaries of perovskites, endowing an excellent antioxidation property by forming Sn(0), coordinating with SnI, and controlling the perovskite crystallization process.

Interface modification of an electron transport layer using europium acetate for enhancing the performance of P3HT-based inorganic perovskite solar cells.

In recent years, although the power conversion efficiency (PCE) of thermally stable all-inorganic CsPbI perovskite solar cells (PSCs) had shown a great progress, the most reported CsPbI PSCs suffered from the large open-circuit voltage () loss, which is related to severe nonradiative recombination and a mismatch in energy level at the transport layer/perovskite interface. In this work, europium acetate (EuAc) as a multifunction interface material is chosen to modify the TiO/perovskite interface, the crystal quality of CsPbI perovskite films is improved, and both bulk and interfacial defects are reduced effectively. Meanwhile, the energy levels arrangement between TiO and CsPbI perovskites is also optimized, corresponding the raised built-in electric field afford a strength force to accelerate the transport and extraction of charge carriers from CsPbI perovskites to TiO.

Interface Modification of a Perovskite/Hole Transport Layer with Tetraphenyldibenzoperiflanthene for Highly Efficient and Stable Solar Cells.

Interface engineering has been recognized as a very effective method to simultaneously improve both efficiency and stability in perovskite solar cells (PSCs). In this work, we report using an excellent small molecular material tetraphenyldibenzoperiflanthene (DBP) to modify the perovskite/Spiro-OMeTAD interface to achieve significantly improved solar cell performance. It is found that the ultrathin DBP interlayer accelerates hole transfer across the FAMAPbIBr/Spiro-OMeTAD interface and effectively reduces the nonradiative recombination.

Efficiency Enhancement of Perovskite Solar Cells via Electrospun CuO Nanowires as Buffer Layers.

CuO nanowires (NWs) with the diameters ranging from 130 to 275 nm have been successfully prepared by electrospinning technique, followed by a calcination process. Inverted planar heterojunction perovskite solar cells (PSCs) with the structure of indium tin oxide/CuO NWs/poly(3,4-ethylenedioxythiophene) (PEDOT):poly(styrenesulphonate) (PSS)/CHNHPbI/phenyl C-butyric acid methyl ester/Bphen/Ag were designed, achieving a best power conversion efficiency (PCE) of 16.87%, which is 21% improvement compared to that of the control PSCs without CuO NWs.

Performance Enhancement of Small Molecular Solar Cells by Bilayer Cathode Buffer.

An effective composite bilayer cathode buffer structure is proposed for use in small molecular solar cells. CsF was doped in Alq3 to form the first cathode buffer, leading to small serial resistances. BCP was used as the second cathode buffer to block the holes to the electrode.

[Study on the Effects of Alq₃:CsF Composite Cathode Buffer Layer on the Performances of CuPc/C₆₀ Solar Cells].

This paper introduces the methods improving the performance and stability of copper-phthalocyanine(CuPc) / fullerene (C₆₀) small molecule solar cells by using tris-(8-hydroxyquinoline) aluminum(Alq₃): cesium fluoride(CsF) composite cathode buffer layer. The device with Alq₃:CsF composite cathode buffer layer with a 4 wt. % CsF at a thickness of 5 nm exhibits a power conversion efficiency (PCE) of up to 0.

Effects of the introduced single-wall carbon nanotubes on the performance of blue phosphorescence organic light-emitting diodes.

In this paper, the effects of single-walled carbon nanotubes (SWCNTs) on the performance of blue phosphorescence organic light-emitting diodes (OLEDs) are investigated by altering the place of SWCNTs in prepared devices. Three kinds of OLEDs in which SWCNTs are spin-coated between the organic layer and the cathode or doped into the organic emitting layer or into the hole-injection layer are prepared. It is found that the SWCNTs doped into the hole-injection layer can enhance the current efficiency because the SWCNTs can reduce hole transport ability and balance two kinds of carriers.

Characteristics of organic light emitting diodes with vanadium oxide solution-treated indium tin oxide.

The effect of indium tin oxide (ITO) in organic light emitting diodes (OLEDs) treated by vanadium penoxide (V2O5) saturation solution was studied. The device with ITO treated by ultraviolet-ozone (UV-ozone) was fabricated in the same run for comparison. It was found that the V2O5 solution-treated devices have much higher current efficiency compared to the device with bare ITO and UV-ozone-treated ITO as the anode.

[Luminescence characteristics of PVK doped with Eu-complex Eu(UVA)3Phen].

The present work investigates the photoluminescence (PL) and electroluminescence (EL) characteristics of Eu-complex Eu (UVA)3Phen doped PVK with different doping concentrations. The results indicate that there exists Forster energy transfer from PVK to Eu(UVA)3 phen in the mixed system. It can get good color purity by optimizing the doping concentration of host and guest materials.

[Luminescence characteristics of PVK doped with Ir(Fppy)3].

In the present work, the photoluminescence (PL) and electroluminescence (EL) characteristics of Tris[2-(2,4-difluorophenyl)pyridine]iridium(III) (Ir(Fppy)3) doped poly(n-vinylcarbazole) (PVK) with different doping concentrations were investigated. And a blue phosphorescent organic light-emitting diode (OLED) with the structures of ITO/PEDOT : PSS/PVK : Ir(Fppy)3/BCP/Alq3/LiF/Al was fabricated. The experimental results show that the luminescence performances of devices are different as the doping concentration of Ir(Fppy)3 is different.

[Effects of hole-injection layers on the performance of blue organic light-emitting diodes].

The present work investigates the effects of different buffer layers on the performance of blue organic light-emitting diodes (OLEDs), and compares them with the device with no buffer layer. Two kinds of blue OLEDs with 4,4'-bis(2,2'-diphenyl vinyl)-1,1'-biphenyl (DPVBi) as the emitting layer, N, N'-bis-(1-naphthyl)-N, N'-1-diphenyl-1,1 '-biphenyl-4, 4'-diamine (NPB) as the hole transporting layer, and copper phthalocyanine (CuPc) and poly(3,4-ethylenedioxythiophene) : poly (styrenesulphonate) PEDOT : PSS as the hole injection layer respectively were fabricated with the structures of ITO/CuPc/NPB/DPVBi/BCP/Alq3 /Al and ITO/PEDOT : PSS/NPB/DPVBi/BCP/Alq3/Al. Moreover, the effects of different preparation technology of CuPc on the performance of OLEDs were also investigated.

[Study on growth mechanism and crystallization phase state of pentacene thin films on p-Si wafer].

The growth mechanism and crystallization phase state were investigated by the methods of atomic force microscopy (AFM) and X-ray diffraction (XRD). The pentacene films were deposited with a self-assembling monolayer by thermal evaporation on p(+)-Si wafer substrates at room temperature and annealed at a constant temperature (80 degrees C) for 120 min. The experimental results show that pentacene films were grown with terraces island structure with the diameter of island of about 100 nm and constituted a layer consisting of faceted grains with a average step height between terraces of 1.