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Purpose: To develop a tablet-based participation measure and to evaluate its reliability and acceptability to an older Chinese population in rehabilitation settings. Method: A multidimensional, self-reported participation measure, the Participation Measure–3 Domains, 4 Dimensions (PM-3D4D), was programed into mobile application software and presented on tablet computers. To explore the reliability of the tablet-based PM-3D4D, 80 adults in rehabilitation outpatient settings aged ≥65 years completed the tablet and the paper versions of the measure at baseline and at 1-week follow-up. Intraclass correlation coefficients were calculated for concordance and test-retest reliability. Participants' acceptability toward the two versions of the measure was described. Results: The tablet-based PM-3D4D showed good to excellent test-retest reliability (Intraclass correlation coefficients = 0.79 ∼ 0.96) and high concordance with the paper-form (Intraclass correlation coefficients = 0.74–1.00). Approximately, 44% participants reported preference for the tablet-based measure, and 20% reported preference for the paper-form measure. Many participants found the tablet-based measure user-friendly, convenient, and environmentally-friendly. Conclusions: Findings of this study provide supportive evidence for administering the tablet-based PM-3D4D to an older Chinese population in rehabilitation settings and suggest a promising measurement methodology for future clinical practice. The developed tablet-based participation measure, the Participation Measure–3 Domains, 4 Dimensions (PM-3D4D), fills a critical void for an efficient and reliable rehabilitation outcome measure tailored to the needs of older adults in rehabilitation settings. The tablet-based PM-3D4D is a reliable outcome measure. Most of the older adults in rehabilitation settings preferred to use the tablet-based participation measure than the paper-form measure; and very few of them reported difficulty with using the tablet-version measure. A high concordance was found between data collected by the tablet version PM-3D4D and data collected by the paper version PM-3D4D. [ABSTRACT FROM AUTHOR]

This work reports warm white light-emitting diodes (WLEDs) using organic–inorganic halide perovskite materials coated YAG:Ce 3+ phosphors by a liquid phase synthesis method. The perovskite MAPbBr 3−x I x -coated YAG:Ce 3+ phosphors have more red light contribution than YAG:Ce 3+ phosphors without the perovskite coating. The chromaticity coordinate of white LED with YAG:Ce 3+ remote phosphor is (x = 0.3134, y = 0.3497) 6359. However, those of MAPbBr 2.5 I 0.5 and MAPbBr 2.0 I 1.0 -coated YAG:Ce 3+ remote phosphor shift to (x = 0.4220, y = 0.3725) 2908 and (x = 0.4067, y = 0.4028) 3525, respectively. The colors of perovskite-coated samples are more red and warm. Therefore, the perovskite-coated YAG:Ce 3+ method is useful for warm WLED. [ABSTRACT FROM AUTHOR]

This work presents an ultrasonic synthesis method for perovskite quantum dots (QDs). The structure, particle size and morphology of perovskite quantum dots were analyzed, and the differences between the dispersion of the organic perovskite quantum dots prepared with and without the ultrasonic treatment were discussed. The results showed that the ultrasonic synthesis contributed to smaller particle sizes and a more uniform particle-size distribution. Tunable emission peaks and adsorption edges of CH 3 NH 3 PbX 3 (X = Cl, Br and I) QDs prepared with different chemical compositions were also generated using the ultrasonic synthesis method, and hence, an extremely wide color gamut was obtained. [ABSTRACT FROM AUTHOR]

Inverted-type perovskite solar cells offer the potential of fabrication by low-temperature solution processing as an alternative to conventional-type perovskite solar cells. PEDOT:PSS is commonly used as the hole transport layer (HTL), but its acidic nature may damage the reliability and stability of the photovoltaic device. In this study, we demonstrate the use of MoO x and WO x HTLs as an alternative to PEDOT:PSS for planar CH 3 NH 3 PbI 3 perovskite solar cells. Furthermore, the MoO x and WO x HTLs are treated using a UV-ozone treatment to improve the surface coverage of the perovskite layer. The resultant conversion efficiency (PCE) for the best cells at AM1.5G illumination with a shadow mask was 13.1%. [ABSTRACT FROM AUTHOR]

This paper reports on the fabrication of ZnO nanowalls for use as an electron collecting layer (ECL) in CH 3 NH 3 PbI 3 perovskite solar cells (PSCs). Two-dimension ZnO nanowalls were grown using a low-temperature chemical bath method with a thin Al film as a seed layer. We compared electron collecting layers based on nanowalls and sol–gel derived ZnO thin film in PSCs and sought to identify the mechanism underlying the collection of electrons. The proposed ZnO nanowalls achieved a fill factor significantly higher than that of ZnO thin films, which translated into a remarkable improvement in power conversion efficiency, reaching 13.6% under AM 1.5G illumination. [ABSTRACT FROM AUTHOR]

AlN thin films were deposited on Pt/Ti/SiO 2 /Si substrates using a radio-frequency magnetron sputtering technique. The effect on the switch current–voltage characteristics of four different materials in the electrode fabricated on top of the AlN film was investigated. The deposition time and nitrogen content in the sputtering atmosphere were changed to adjust the thickness and composition of the AlN thin films, respectively. The influence of film thickness and content on the resistive switching behavior was discussed. The possible mechanism of resistive switching was examined via analyses of the electrical resistive switching characteristics, forming voltage, and on/off current ratio. [ABSTRACT FROM AUTHOR]

• A ligand-exchange reaction using TOAB was present for stable CsPbI 3−x Br x quantum dots. • TOAB-passivated QDs showed environmental resistance, such as, moisture, light, and heat. • TOAB-passivated devices exhibited a maximum luminescence of 1345 cd/m2 and a maximum external quantum efficiency of 11.7%. In this study, we demonstrate a ligand-exchange reaction using tetraoctylammonium bromide (TOAB) salts for the as-synthesized CsPbI 3 perovskite nanoparticles (NPs) to ensure NPs with stable and improved device performance. TOAB passivation provides a negatively polarized halide-rich surface, higher steric hindrance, and a small amount of Br− anions in the NP lattice to significantly improve the NP stability. The red NP-based light-emitting diodes (NpLEDs) based on TOAB-passivated NPs also exhibited excellent performance because of shorter ligands and stable NPs, with a maximum luminescence of 1345 cd/m2 and a maximum external quantum efficiency of 11.7%. [ABSTRACT FROM AUTHOR]

Abstract: Al-doped ZnO (AZO) films with a thickness of ∼400nm were prepared by sputtering on glass substrates for use as transparent anodes of organic light-emitting diodes (OLED) devices. The operation voltages (at 100cd/m2) of OLED devices with AZO and ITO anode materials were 10.5 and 5.5V, respectively. The maximum luminance output of the AZO device was 6450cd/m2 (achieved at 12.5V) and that of the ITO device was 9830cd/m2 (achieved at 10.5V). We demonstrate that a hole-only device method can be used to estimate the suitability of AZO and ITO anodes in the OLED devices and to verify experimental results. The AZO thin films with low price and non-toxicity may be suitable as alternative anodes in OLED devices under high voltage. [Copyright &y& Elsevier]

The unipolar resistive switching behavior of Pt/LixZn1-xO/Pt structures fabricated via radio-frequency magnetron sputtering is investigated. Various Li doping concentrations influence the defect types (i.e., VO, Lii, and LiZn) in LixZn1-xO films for adjustable resistance ratio. The resistance ratio reaches 108 due to the minimized leakage current in the high-resistance state (HRS) at 6 at. % Li dopants. The dominant conduction mechanisms are explained in terms of Ohmic behavior and Poole-Frenkel (PF) emission. The coefficient r of the PF emission in the HRS is evaluated to confirm that the total number of defects in LixZn1-xO films decreases with increasing Li content. [ABSTRACT FROM AUTHOR]

Organic light-emitting diodes (OLEDs) have developed rapidly in recent years. Thermally activated delayed fluorescent (TADF) molecules open a path to increase exciton collection efficiency from 25% to 100%, and the solution process provides an alternative technology to achieve lower cost OLEDs more easily. To develop commercial materials as exciplex hosts for high-performance and solution-processed OLEDs, we attempted to use 4,4′-cyclohexylidenebis[N,N-bis(4-methylphenyl)benzenamine (TAPC), poly(9-vinylcarbazole) (PVK), N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (NPB), and poly(N,N'-bis-4-butylphenyl-N,N'-bisphenyl)benzidine (Poly-TPD) as the donors and 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (POT2T) as the acceptor to obtain the TADF effect. All donors and the acceptor were purchased from chemical suppliers. Our work shows that excellent TADF properties and high-efficiency exciplex OLEDs with low turn-on voltage and high luminance can be achieved with a simple combination of commercial materials. [ABSTRACT FROM AUTHOR]

In this study, the performances of red CsPbI3-based all-inorganic perovskite quantum-dot light-emitting diodes (IPQLEDs) employing polymeric crystalline Poly(3-hexylthiophene-2,5-diyl) (P3HT), poly(9-vinycarbazole) (PVK), Poly(N,N′-bis-4-butylphenyl-N,N′-bisphenyl)benzidine (Poly-TPD) and 9,9-Bis[4-[(4-ethenylphenyl)methoxy]phenyl]-N2,N7-di-1-naphthalenyl-N2,N7-diphenyl-9H-fluorene-2,7-diamine (VB-FNPD) as the hole transporting layers (HTLs) have been demonstrated. The purpose of this work is an attempt to promote the development of device structures and hole transporting materials for the CsPbI3-based IPQLEDs via a comparative study of different HTLs. A full-coverage quantum dot (QD) film without the aggregation can be obtained by coating it with VB-FNPD, and thus, the best external quantum efficiency (EQE) of 7.28% was achieved in the VB-FNPD device. We also reported a standing method to further improve the degree of VB-FNPD polymerization, resulting in the improved device performance, with the EQE of 8.64%. [ABSTRACT FROM AUTHOR]

A hybrid resistance switching device consisting of ZnO nanorods embedded in an insulating polymethylmethacrylate (PMMA) heterostructure sandwiched between a transparent conductive film and an Al electrode is proposed. The current-voltage characteristics of the device are discussed in terms of the formation and rupture of its conductive filaments. The hybrid device shows stable electrical bistable behaviors after more than 200 resistance-switching cycles. The hybrid ZnO nanorod/PMMA device presented in this work has potential applications in the field of bistable random access memory devices. [ABSTRACT FROM AUTHOR]

In recent years, the remarkable optoelectronic characteristics exhibited by perovskite quantum dots (PQDs) have captured significant attention, which has spurred numerous investigations and novel applications. Nonetheless, the development of solution‐processed upconversion devices (UCDs) has predominantly centered around the utilization of organic materials, 3D perovskite films, and II‐VI quantum dots. In this work, PQDs are utilized for the first time as emission materials to enhance UCD performance. The stability of PQDs, synergistic coverage effect between PQDs and hole‐transporting layers (HTLs), and the interfaces of CGL/HTL are investigated in an attempt to identify the primary factor affecting UCD performance. The optimized UCD incorporating with effective TAPC HTLs demonstrate a maximum luminance of 463.9 cd m−2 at 520 nm (biased at 12 V and irradiated under 785 nm NIR light) accompanied by significant current gains of 167 times (at 3.4 V) and a noteworthy photon‐to‐photon conversion efficiency of 5.68% (at 12 V). The impressive performance is accompanied by a remarkably low turn‐on voltage of 1.4 V and a high leakage voltage of up to 12 V, making the highest record reported for solution‐processed UCDs. [ABSTRACT FROM AUTHOR]

Perovskite quantum dots (QDs) have showed excellent optoelectronic properties to extend the application range of novel solid-state lighting, such as perovskite QD based LEDs (QD-LEDs). However, the traditional device structure of perovskite QD-LEDs employed PEDOT:PSS as a hole inject layer (HIL), which impairs stability due to acidic surface characteristics. This study proposes the sputtered NiO films as an HIL to replace acidic PEDOT:PSS. The NiO films with significantly different characteristics were prepared by controlling the sputtering parameters to investigate the devices' performance of NiO-based CsPbBr3 QD-LEDs. The optimized device showed an excellent performance with maxima luminescence of 20,118 cd/m2 and an external quantum efficiency (EQE) up to 3.63%. [ABSTRACT FROM AUTHOR]

Sputtering made ZnO thin film was used as an electron-transport layer in a regular planar perovskite solar cell based on high quality CH3NH3PbI3 absorber prepared with a two-step spin-coating. An efficiency up to 15.9% under AM 1.5G irradiation is achieved for the cell based on ZnO film fabricated under Ar working gas. The atmosphere of the sputtering chamber can tune the surface electronic properties (band structure) of the resulting ZnO thin film and therefore the photovoltaic performance of the corresponding perovskite solar cell. Precise surface engineering of ZnO thin film was found to be one of the key steps to fabricate ZnO based regular planar perovskite solar cell with high power conversion efficiency. Sputtering method is proved to be one of the excellent techniques to prepare ZnO thin film with controllable properties. [ABSTRACT FROM AUTHOR]

The thermal stability of (Mg0.95Ni0.05)2TiO4 dielectric ceramics has been improved by mixing with CaTiO3 phases owing to higher positive temperature coefficients. The pure (Mg0.95Ni0.05)2TiO4 and the mixture phase systems of CaTiO3-modified (Mg0.95Ni0.05)2TiO4 were verified by XRD diffraction patterns to ensure the crystallite of different phases. The microstructures of the CaTiO3-modified (Mg0.95Ni0.05)2TiO4 were observed by SEM and EDS to investigate the relation between element ratios and grains. As a result, it can be seen that the thermal stability of the CaTiO3-modified (Mg0.95Ni0.05)2TiO4 can be effectively enhanced, compared with the pure (Mg0.95Ni0.05)2TiO4. Moreover, the radio frequency dielectric performances of CaTiO3-modified (Mg0.95Ni0.05)2TiO4 dielectric ceramics are strongly dependent upon the density and the morphology of the specimens. The champion sample with the ratio of (Mg0.95Ni0.05)2TiO4 and CaTiO3 of 0.92:0.08 showed an εr value of 19.2, an Qf value of 108,200 GHz, and a τf value of −4.8 ppm/°C, which may encourage (Mg0.95Ni0.05)2TiO4 ceramics to broaden the range of novel applications and match the requirements of 5G or next-generation communication systems. [ABSTRACT FROM AUTHOR]

In this study, blue perovskite quantum dots (PQDs) were prepared using didodecyldimethylammonium bromide (DDAB), which can passivate surface defects caused by the loss of surface ligands and reduce particle size distribution. After the passivation of DDAB, blue CsPbClxBr3−x PQDs dispersed in n-octane produced a more compact and uniform PQD thin film than the non-passivated ones. The resulting device showed a stabile lifetime, and an EL peak of 470 nm and a maximum EQE of 1.63% were obtained at an operating voltage of 2.6 V and a current density of 0.34 mA/cm2. This work aims to provide a simple method to prepare blue-emitting PQDs and high-performance PQD-based light-emitting devices. [ABSTRACT FROM AUTHOR]

Stretchable microcavity lasers reveal potential application in flexible displays, biomedicine, and wearable devices in the near future. In this work, we investigated the characteristic of amplified spontaneous emission (ASE) from all inorganic CsPbBr3 QDs on a flexible PET substrate with the assistance of biocompatible silk fibroin (SF) film. In comparison with the sample on PET directly, the ASE of all-inorganic perovskite film revealed a lower threshold of 32.7 μJ/cm2, higher slope efficiency, and a larger gain coefficient of around 100.0 cm−1 owing to the better stack and good arrangement of the CsPbBr3 QDs on top of the SF film. For the temperature-dependent ASE measurement, the larger characteristic temperature of around 277 K is obtained from CsPbBr3 QD/SF film, and the emission peak reveals a slight shift with temperature variation, which indicates its temperature-insensitive property. As the curvature of flexible substrate increases under the mechanical bending, the lasing threshold of CsPbBr3 QD/SF film was reduced along with the increase in slope efficiency owing to the enhancement in the index guiding effect. [ABSTRACT FROM AUTHOR]

Stretchable microcavity lasers reveal potential application in flexible displays, biomedicine, and wearable devices in the near future. In this work, we investigated the characteristic of amplified spontaneous emission (ASE) from all inorganic CsPbBr3 QDs on a flexible PET substrate with the assistance of biocompatible silk fibroin (SF) film. In comparison with the sample on PET directly, the ASE of all-inorganic perovskite film revealed a lower threshold of 32.7 μJ/cm2, higher slope efficiency, and a larger gain coefficient of around 100.0 cm−1 owing to the better stack and good arrangement of the CsPbBr3 QDs on top of the SF film. For the temperature-dependent ASE measurement, the larger characteristic temperature of around 277 K is obtained from CsPbBr3 QD/SF film, and the emission peak reveals a slight shift with temperature variation, which indicates its temperature-insensitive property. As the curvature of flexible substrate increases under the mechanical bending, the lasing threshold of CsPbBr3 QD/SF film was reduced along with the increase in slope efficiency owing to the enhancement in the index guiding effect. [ABSTRACT FROM AUTHOR]

In the article "High-Leakage-Resistance and Low-Turn-On-Voltage Upconversion Devices Based on Perovskite Quantum Dots," Zong-Liang Tseng, Shun-Wei Liu, and their colleagues present a method for improving the leakage resistance and turn-on voltage of solution-processed upconversion devices. They achieve this by using emissive perovskite quantum dots and a hole-transporting layer, which enhance the quality of the quantum-dot films and offer a new approach to designing high-performance upconversion devices. This research provides valuable insights for the development of more efficient and effective upconversion devices. [Extracted from the article]

The poor stability of CsPbX3 quantum dots (QDs-CsPbX3) under wet conditions is still considered to be a key issue. In order to overcome this problem, this study presents a high molecular weight polymer matrix (polymethylmethacrylate, PMMA) incorporated into the QDs-CsPbBr3 to improve its stability and maintain its excellent optical properties. In this study, the Cs2CO3, PbO, Tetrabutylammonium Bromide (TOAB) powder, oleic acid, and toluene solvent were uniformly mixed and purified to prepare high-quality QDs powders. Then, hexane was used as a dispersing agent for the QD powder to complete the perovskite QDs-CsPbBr3 solution. Finally, a solution with different proportions of quantum dots CsPbBr3 and PMMA was prepared and discussed. In the preparation of thin films, firstly, a thin film with the structure of glass/QD-CsPbBr3/PMMA was fabricated in a glove box using a well-developed QDs-CsPbBr3 solution by changing the ratio of CsPbBr3:PMMA. The material analysis of QDs-CsPbBr3 thin films was performed with photoluminescence (PL), transmittance, absorbance, and transmission electron microscopy (TEM). The structures and morphologies were further examined to study the effect of doped PMMA on perovskite QDs-CsPbBr3. [ABSTRACT FROM AUTHOR]

We describe a method to enhance power conversion efficiency (PCE) of MAPbI3 perovskite solar cell by inserting a FAPbX3 perovskite quantum dots (QD-FAPbX3) layer. The MAPbI3 and QD-FAPbX3 layers were prepared using a simple, rapid spin-coating method in a nitrogen-filled glove box. The solar cell structure consists of ITO/PEDOT:PSS/MAPbI3/QD-FAPbX3/C60/Ag, where PEDOT:PSS, MAPbI3, QD-FAPbX3, and C60 were used as the hole transport layer, light-absorbing layer, absorption enhance layer, and electron transport layer, respectively. The MAPbI3/QD-FAPbX3 solar cells exhibit a PCE of 7.59%, an open circuit voltage (Voc) of 0.9 V, a short-circuit current density (Jsc) of 17.4 mA/cm2, and a fill factor (FF) of 48.6%, respectively. [ABSTRACT FROM AUTHOR]

A series of alcohols (methanol, ethanol and isopropyl alcohol) were added to poly(3,4-ethylenedioxythiophene): (polystyrene sulfonate) (PEDOT: PSS) aqueous solutions in order to manipulate the molecular structure of the PEDOT chains in PEDOT: PSS hole transporting materials (HTMs) and thus to improve the power conversion efficiency of CH 3 NH 3 PbI 3 based solar cells. The structural and electronic characteristics of the resultant PEDOT: PSS HTMs were analyzed using atomic-force microscopy, contact angle measurement, Raman scattering spectrometry and photoelectron spectrometry. The properties of the PEDOT: PSS thin films could be controlled by tuning the viscosity of the PEDOT: PSS solutions. High viscosity PEDOT: PSS solutions resulted in linear structured PEDOT chains, which increased the work function of the PEDOT: PSS HTMs thereby improving the open-circuit voltage of the CH 3 NH 3 PbI 3 solar cells. The surface roughness and surface free energy of the PEDOT: PSS HTMs influence the structural properties of CH 3 NH 3 PbI 3 thin films, which determines the exciton dissociation at the CH 3 NH 3 PbI 3 /PEDOT: PSS interface (short-circuit current density) and the carrier recombination at the CH 3 NH 3 PbI 3 /[6,6]-phenyl-C61-butyric acid methyl ester (PC 61 BM) interface (fill factor). In addition, it is predicted that the power conversion efficiency can be further improved by increasing the crystallinity of the CH 3 NH 3 PbI 3 thin film. [ABSTRACT FROM AUTHOR]

A series of nonpolar antisolvents (chlorobenzene, bromobenzene, iodobenzene and toluene) were used to assist in the formation of smooth and crystalline CH 3 NH 3 PbI 3 thin films by a one-step spin-coating method. The structural, optical and excitonic characteristics of the resultant CH 3 NH 3 PI 3 thin films were analyzed using an atomic-force microscope, X-ray diffractometer, absorbance spectrum, photoluminescence (PL) spectrum, time-resolved PL and temperature-dependent PL. The properties of the CH 3 NH 3 PbI 3 thin films are dependent on the relative polarity and boiling point of the nonpolar antisolvents used in the washing treatment process. The interplay between nucleation (relative polarity) and crystal growth (boiling point) during the formation of CH 3 NH 3 PbI 3 thin films influences the short-circuit current density (J SC ) and power conversion efficiency (PCE) of the corresponding solar cells. The experimental results demonstrate that iodobenzene can be substituted for toluene as a more efficient antisolvent in the washing treatment process during the fabrication of CH 3 NH 3 PbI 3 thin films. In addition, it is predicted that the J SC and PCE can be further improved by increasing the crystallinity of the CH 3 NH 3 PbI 3 thin film. [ABSTRACT FROM AUTHOR]

This paper reports on a solvothermal method used in the fabrication of vertically aligned two-dimensional (2D) ZnO nanowall networks and one-dimensional (1D) ZnO nanorods with overlapping structures. The introduction of an Al thin film as a doping source was shown to alter the morphology from rods to walls. The proposed multilayer buffer results in the formation of two types of nanostructure (nanowalls and rods) and also increased the length to which the nanorods grow at the same time. Analysis based on transmission electron microscopy (TEM) and selected area electron diffraction (SAED) led us to formulate a possible growth mechanism and elucidate the optical properties of the ZnO nanostructures. [ABSTRACT FROM AUTHOR]

The multicrystalline grain size of CH 3 NH 3 PbI 3 thin films can be manipulated by using different precursor concentrations which dominate the competition between the nucleation and crystal growth during the one-step spin-coating process with the toluene washing treatment. A comprehensive study was carried out to explore the correlation between the structural properties and the exciton dynamics in CH 3 NH 3 PbI 3 thin films fabricated using various precursor concentrations from 1.25 M to 1.65 M. The experimental results show that the precursor concentration influences the grain size and exciton dynamics of the resultant CH 3 NH 3 PbI 3 thin films which were fabricated on top of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate/ITO/glass substrates. The higher average power conversion efficiency (PCE) of 13.66% achieved can be explained as being due to the formation of a larger CH 3 NH 3 PbI 3 grain size which thus results in higher photocurrent generation and lower voltage loss. It is predicted that the PCE can be further improved when the voltage loss across the CH 3 NH 3 PbI 3 thin film is minimized. [ABSTRACT FROM AUTHOR]

A phase-pure mixed-organic-cation perovskite absorber (MOC-PA) was fabricated by a one-step spin-coating process with a toluene washing treatment, and the structural, optical and excitonic properties of the resultant MOC-PAs were then characterized by scanning electron microscopy, X-ray diffractometry, absorbance spectrometer, and time-resolved photoluminescence. The averaged power conversion efficiency (PCE) of inverted phase-pure MOC-PA based photovoltaics could be improved from 12.21% to 13.28% by tailing the surface roughness of the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thin film from 1.43 nm to 1.84 nm. The improved PCE is mainly due to the increased short-circuit current density ( J SC ) which is attributed to the improvement of the exciton dissociation, as confirmed by photoluminescence experiments. In addition, the experimental results indicate that the PCE can be further improved by increasing the crystallinity of MOC-PAs. [ABSTRACT FROM AUTHOR]

This paper reports a novel method for the synthesis of ZnO nanorods, nanowalls, and nanorod/wall structures directly on a substrate, using a simple chemical bath deposition process. The morphology of the resulting structures can be altered simply by adjusting the thickness of an Al thin film, which is used as a doping source. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) measurements revealed that the resulting ZnO formations possess a wurtzite structure. Inductively coupled plasma mass spectrometry (ICP-MS) revealed that the Al doping of the nanostructures is between 2.1 at% and 4.9 at%. The predominance of violet-blue emissions in the CL spectra of Al-doped and undoped ZnO indicates the presence of interstitial zinc (Zn i ) and zinc vacancies (V Zn ). In this study, the work function was adjusted between 3.81 and 4.39 eV simply by varying the thickness of the Al reaction source. [ABSTRACT FROM AUTHOR]

Comprehensive studies were carried out to understand the thickness effects of ZnO thin films for tri-iodide perovskite absorber (TPA) based photovoltaics, including the absorption spectrum, photoluminescence, nanosecond time-resolved photoluminescence (NTRPL), and photo-induced absorption (PIA) of TPA/ZnO/ITO/glass. These were carried out in order to explore the Urbach energy of TPA films and the exciton dissociation at the interface between TPA and ZnO. The results show that the thickness of the ZnO thin film significantly influences the photovoltaic performance in terms of open-circuit voltage ( V OC ), fill factor (FF), and short-circuit current density ( J SC ). In the case of the thicker ZnO film, the photovoltaics have the better FF and V oc , as a result of the smaller electron recombination. This means that a thicker ZnO film can block the electron recombination from the Fermi level of the ITO to the valance band of the TPA. On the other hand, the thicker ZnO film results in a higher J SC due to the better exciton dissociation at the interface between TPA and ZnO, which means that the electron mobility of the thicker ZnO is higher. Consequently, the photovoltaic performance can be expected to be improved by using a transparent cathode electrode with high conductivity and electron mobility. [ABSTRACT FROM AUTHOR]

All inorganic perovskite quantum dots (PQDs) and perovskite CsPbX 3 /SiO 2 nanocomposites (PNCs) have shown their potentials for optical and lighting applications. We demonstrate a one-step approach to synthesize PQDs and PNCs more simply and effectively at room temperature in the open air. The resulting PNCs can show a narrow emission in the PL spectra and high stability under ambient conditions. In particular, both green CsPbBr 3 /SiO 2 and red CsPbI 3-x Br x /SiO 2 PNCs can be obtained by employing this easy and low-cost method. Even, the SiO 2 protection can also effectively prevent the halide exchange reaction between green and red PNCs, meaning the capability for white light applications. The resulting white light-emitting diodes (WLEDs) based on the green and red PNCs coated on the blue LED have a white Commission Internationale del' Enclairage (CIE) coordinates of (0.375, 0.362) and a low correlated color temperature (CCT) of 4054 K. [ABSTRACT FROM AUTHOR]

Abstract: An improvement of photovoltaic characteristics has been demonstrated in heterojunction organic photovoltaic (OPV) cells with a ITO/copper phthalocyanine (CuPc)/C60/ bathocuproine (BCP)/LiF/Al configuration by doping tris (8-hydroxyquinoline) aluminum (Alq3) fluorescent dye into the acceptor (or donor) layers. With Alq3 doping, the short-circuit current density (J SC) increased from 8.25 to 12.23 mA/cm2, the open-circuit voltage (V OC) increased from 0.50 to 0.62 V, and the power conversion efficiency (η p) increased from 1.76 to 2.57% under 100 mW/cm2 AM 1.5 illumination. These improvements can be attributed to the increased light absorption caused by Alq3, which led to more effective exciton formation. The energy difference between the highest occupied molecular orbital (HOMO) of the donor and the lowest unoccupied molecular orbital (LUMO) of the acceptor in the doped device increased, leading to a larger V OC. There are no photoluminescence (PL) in the Alq3-doped C60 layer, suggesting that the formation of Alq3 excitons was followed by energy transfer or charge transfer to C60 under illumination in the doped layer. The conversion efficiency of OPV cells was thus improved. [Copyright &y& Elsevier]

Abstract: The advantages of using an anode buffer layer of ZnO on the electro–optical properties of organic light emitting devices (OLEDs) are reported. ZnO powders were thermal-evaporated and then treated with ultra-violet (UV) ozone exposure to make the ZnO layers. The turn-on voltage of OLEDs decreased from 4V (4.2cd/m2) to 3V (3.4cd/m2) and the power efficiency increased from 2.7lm/W to 4.7lm/W when a 1-nm-thick ZnO layer was inserted between indium tin oxide (ITO) anodes and α-naphthylphenylbiphenyl diamine (NPB) hole-transporting layers. X-ray and ultra-violet photoelectron spectroscopy (XPS and UPS) results revealed the formation of the ZnO layer and showed that the work function increased by 0.59eV when the ZnO/ITO layer was treated by UV-ozone for 20min. The surface of the ZnO/ITO film became smoother than that of bare ITO film after the UV-ozone treatment. Thus, the hole-injection energy barrier was lowered by inserting an ZnO buffer layer, resulting in a decrease of the turn-on voltage and an increase of the power efficiency of OLEDs. [Copyright &y& Elsevier]

In this paper, a thermally crosslinkable 9,9-Bis[4-[(4-ethenylphenyl)methoxy]phenyl]-N2,N7-di-1-naphthalenyl-N2,N7-diphenyl-9H-fluorene-2,7-diamine (VB-FNPD) film served as the hole transporting layer (HTL) of perovskite CsPbBr3 quantum-dot light-emitting diodes (QD-LEDs) was investigated and reported. The VB-FNPD film crosslinked at various temperatures in the range of 100~230 °C followed by a spin-coating process to improve their chemical bonds in an attempt to resist the erosion from the organic solvent in the remaining fabrication process. It is shown that the device with VB-FNPD HTL crosslinking at 170 °C has the highest luminance of 7702 cd/m2, the maximum current density (J) of 41.98 mA/cm2, the maximum current efficiency (CE) of 5.45 Cd/A, and the maximum external quantum efficiency (EQE) of 1.64%. Our results confirm that the proposed thermally crosslinkable VB-FNPD is a candidate for the HTL of QD-LEDs. [ABSTRACT FROM AUTHOR]

CH 3 NH 3 PbI 3 (MAPbI 3) perovskite thin films were fabricated by using the one-step spin-coating method with a washing-enhanced nucleation (WEN) process under various dropping times, and the resultant thin films were characterized through the reflected-type optical microscope, atomic force microscope, transmittance spectrometer, X-ray diffractometer, photoluminescence spectrometer and water droplet contact-angle imaging system. The experimental results show that the dropping time for the WEN process strongly influences the surface morphology, surface wettability, crystallinity and refractive index of the resultant MAPbI 3 thin films, which dominates the contact at the hydrophilic MAPbI 3 /hydrophobic 6,6-phenyl C 61 butyric acid methyl ester (PCBM) interface and thereby determines the photovoltaic performance. In addition, this investigation helps further understand the effects of the WEN process on the formation of a closely-packed MAPbI 3 thin film. Image 1 • The dropping time for the WEN process highly influences the formation of perovskite films. • The dropping time largely changes the optical and structural properties of perovskite films. • The dropping time can change the surface wettability of perovskite films. • The dropping time dominates the photovoltaic performance of perovskite solar cells. [ABSTRACT FROM AUTHOR]

High-quality perovskite CsPbBr3 quantum dots (QDs-CsPbBr3) were prepared using the ultrasonic oscillation method, which is simple and provides variable yield according to requirements. The emission spectra over a large portion of the visible spectral region (450–650 nm) of QD-CsPbX3 (X = Cl, Br, and I) have tunable compositions that can be halide exchanged using the halide anion exchange technique and quantum size-effects. A strong peak with high intensity of (200) lattice plane of purified QDs-CsPbBr3 film is obtained, confirming the formation of an orthorhombic perovskite crystal structure of the Pnma space group. The photoluminescence of QDs-CsPbBr3 was characterized using a narrow line-width emission of 20 nm, with high quantum yields of up to 99.2%, and radioactive lifetime increasing to 26 ns. Finally, through the excellent advantages of QDs-CsPbBr3 mentioned above, purified perovskite QDs-CsPbBr3 as an active layer was utilized in perovskite quantum dot light-emitting diodes structure applications. As a result, the perovskite QDs-CsPbBr3 light-emitting diodes (LEDs) exhibits a turn-on voltage of 7 V and a maximum luminance of 5.1 cd/m2. [ABSTRACT FROM AUTHOR]

Perovskite CsPbBr3 quantum dot (CsPbBr3-QD) recovery was performed using lead scrap from lead storage batteries. The perovskite CsPbBr3-QD characteristics were analyzed using different PbO/recycled PbO2 ratios. Scanning electron microscopy (SEM) was used to observe the film surface morphology and cross-section. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) were used to observe the perovskite CsPbBr3-QDs' structural characteristics. A photoluminescence (PL) measurement system was used to analyze the optical properties. The results show that lead scrap from lead–acid batteries as a material for perovskite CsPbBr3-QD production can be successfully synthesized. This saves material and also proves that recycling is valuable. The proposed approach is helpful for future material shortages and materials not easily accessible. Although the efficiency is not very high, this process will be purified using recycled lead in the future to achieve higher quantum yield. [ABSTRACT FROM AUTHOR]

Li-doped zinc oxide (L0.03Z0.97O) thin films are deposited onto Pt/Ti/SiO2/Si substrates via the radio frequency magnetron sputtering method. The structure evolution with annealing temperature of the predominantly (002)-oriented Li-doped ZnO (LZO) films after in-situ post-annealing process is determined. The largest values of the piezoelectric coefficient (d33) and the remnant polarization (Pr) (22.85 pm/V and 0.655 μC/cm2, respectively) are obtained for LZO films post-annealed at 600 °C, which can be attributed to the predominant (002)-oriented crystalline structure, the release of intrinsic residual compressive stress, and less non-lattice oxygen. [ABSTRACT FROM AUTHOR]