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In our previous work, the device performance of polymer solar cells (PSCs) was enhanced by blending surfactant-treated graphene oxide (GO) nanocomposites [didodecyldimethyla-mmonium bromide (DDAB):GO] as the active layer. However, its underlain mechanism is not clearly reported. In this work, therefore we measured the charge carriers mobility of the active layers before and after blending GO:DDAB nanocomposites to reveal the role of GO:DDAB in PSCs, and found that GO:DDAB can form three-dimensional network for charge carriers transport, meanwhile ‘traps’ for electrons can be introduced by GO:DDAB and formed in the bulk and/or at active-layer/electrode interfaces, compromising the electron mobility. Meanwhile, the hole mobility was improved due to the enhanced crystallinity of the composite films after blending GO:DDAB into P3HT:PCBM. Therefore, the transport balance between electrons and holes is enhanced and thus the device performance is improved. [ABSTRACT FROM AUTHOR]

• This paper evaluates the effect of carbon emission trading policy on firm's environmental investment. • The establishment of a carbon emission trading system imposes a negative effect on corporate environmental investment. • The effect is particularly pronounced in NonSOEs and large firms. • Potential mechanisms is that productive investment crowds out the green investment. This paper evaluates the effect of carbon emission trading policy on firm's environmental investment based on the Difference-in-Differences method. The result shows that the establishment of a carbon emission trading system imposes a negative effect on corporate environmental investment. Furthermore, our findings reveal that the reduction in environmental investment arising from carbon emission trading policy is particularly pronounced in non-state-owned enterprises and mature enterprises with large-size. The analysis of potential mechanisms implies that productive investment crowds out the green investment due to the carbon emission regulation. Overall, this study is conducive to the current environmental policy debates by informing policymakers about the implications of investment decision-making behavior of microcosmic enterprises in response to the carbon emission trading policy. [ABSTRACT FROM AUTHOR]

Colloidal quantum dots (CQDs) are attractive materials for optoelectronic applications due to their low-cost, facile processing and size-dependent band-gap tunability. Solution-processed organic, inorganic and hybrid ligand-exchange techniques have been widely applied in QDs-based solar cells (QDSCs) to improve the power conversion efficiency (PCE). Till now, however, few have been reported to date the influence of post-synthesis annealing on the electrical characteristics of the PbS QDSCs. To reduce the influence of diffusion length, in this work, we present the thermal annealing treatment effect on the device performance of a typical heterojunction solar cell ITO/ZnO/PbS/Au with a relatively thinner active layer. By changing the annealing temperatures during the post-synthesis processes, we found its PCE increase from 3.26% to 4.52% after annealing at 140 °C, showing a 38.6% enhancement due to a dramatic enhancement of short circuit-current density ( J SC ) but a slight decrement of open-circuit voltage ( V OC ), and also, the mechanisms underneath for the enhanced performance are discussed in details. [ABSTRACT FROM AUTHOR]

Usually, the drain-source current ( I DS ) increases with positive drain-source voltage ( V DS ) for pentacene-based organic static induction transistor (OSIT) ITO(Source)/Pentacene/Al(Gate)/Pentacene/Au(Drain) and it shows an inherent rectifying property under negative gate voltages ( V G ), i.e. the slope of I DS vs. V DS curve increases with V DS but without any current saturation effect. In this paper, we investigated the electrical characteristics of pentacene-based OSIT ITO/Pentacene(80 nm)/Al(15 nm)/Pentacene(80 nm)/Au under negative V DS and V G , and found that I DS changed from rectifying property to saturation effect when the magnitude of negative V DS was increased from 0 V to −6 V under negative V G , and the turn-on voltage ( V ON ) moved to larger negative voltages when the magnitude of negative V G increased and the movement step of V ON gets smaller after keeping the device for a long time, and the possible mechanisms for such a kind of current modulation were discussed. [ABSTRACT FROM AUTHOR]

Being the unique physical structure and excellent optoelectronic properties, silicon nanowires (Si-NWs) array is considered to be a key nanostructure to build low-cost and high-efficiency solar cells, showing excellent performance of photons capturing and anti-reflection. In this work, the light absorption enhancement of Si-NWs array based solar cells by filling plasmonic metal nanoparticles (NPs), such as Au, Ag and Al, and/or PbS quantum dots (QDs) in the gaps of Si-NWs or depositing on the tips of Si-NWs, are simulated by using finite-difference time-domain (FDTD) software, respectively. Based on the proposed geometry of periodic Si-NWs array, our simulation demonstrates that the light absorption in the long-wavelength region can be greatly enhanced by filling suitable metal NPs or PbS QDs to form a certain thickness layer or depositing metal NPs on the tips of Si-NWs, by making good use of the localized surface plasmons and scattering generated around metal NPs, or the high absorption of PbS QDs in near-infrared region. Also, our simulation is in agreement with experimental data reported in literatures. Therefore, our work provides a valuable theoretical basis for designing high-performance Si-NWs array based solar cells. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the roles of zinc selenide (ZnSe) sandwiched between organic layers, i.e. organic/ZnSe/aluminum quinoline (Alq3), have been studied by varying device structure. A broad band emission was observed from ITO/poly(N-vinylcarbazole)(PVK)(80 nm)/ZnSe(120 nm)/ Alq3(15 nm)/Al under electric fields and it combined the emissions from the bulk of PVK, ZnSe and Alq3, however, emission from only Alq3 was observed from trilayer device ITO/,-bis-(1-naphthyl)-,-diphenyl-1, 1′-biphenyl-4, 4′-diamine (NPB) (40 nm)/ZnSe(120 nm)/ Alq3(15 nm)/Al. Consequently the luminescence mechanism in the ZnSe layer is suggested to be charge carrier injection and recombination. By thermal co-evaporating Alq3 and 4-(dicyanomethylene)-2--butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB), we get white light emission with a Commission Internationale de l’E clairage (C.I.E) co-ordinates of (0.32, 0.38) from device ITO/PVK(80 nm)/ZnSe(120 nm)/ Alq3:DCJTB(0.5 wt% DCJTB)(15 nm)/Al at 15 V and the device performs stably with increasing applied voltages. [Copyright &y& Elsevier]

According to laser beam transporting in a multipass Ti:sapphire amplifier based on a parabolic mirror, the influential factors to induce astigmatism are analyzed. The beam waists of the laser beam transporting in the multipass amplifier are calculated by ABCD law in sagittal and tangential planes, respectively, and are compared with each other. Our analyses of these influential factors provide valuable data to optimize this design of multipass Ti:sapphire amplifier, and our experimental results of getting Gaussian beam from such a kind of amplifier confirmed our theoretical analyses. [Copyright &y& Elsevier]

In this paper, a novel arrangement of multipass Ti:sapphire amplifier based on a parabolic mirror is demonstrated, by using disc-anvil structure. With a 532-nm pump power of 4.1 W, we got 340 mW amplified Gaussian beam centered at 800 nm when seeding 7 nJ 1 kHz pulses, and the efficiency reaches to 8.3%. Since it experiences less dispersion in this novel arrangement, it is much easier to get amplified ultrashort pulses shorter than sub-50-fs from CPA system consisted of this new type of multipass amplifier. [Copyright &y& Elsevier]

In this paper, we design an optical energy harvesting system composed of a magnet with a smooth surface, magnetically levitated pyrolytic graphite, and a light source. A periodic force field was constructed by modulating the light absorption of graphite at different positions through the interference of light on the smooth magnet surface and the linear variation of graphite magnetization with light absorption, thereby driving the graphite to vibrate periodically. It is confirmed in our study that this photo-magnetic effect can convert continuous light energy into vibrational kinetic energy, the driving light intensity can be reduced by 3-4 orders of magnitude and the amplitude can reach tens of microns, and the wavelength range of the driving light can cover the visible and infrared light bands, which makes it possible to develop a new type of light-driven micro-nano mechanical motor or light energy harvesting system. Graphite motion amplitude varies with light power when the magnetic field gradient is 1.1 T/m (black line) and 1.2 T/m (red line), the inset shows the schematic diagram of graphite magnetic levitation and interference light field intensity distribution diagram of light absorption and force variation. [Display omitted] • Energy Harvesting MEMS device based on continuous light-driven spontaneous vibration. • The driving light field can be as low as 0.1mw/cm2. • Wide driving wavelength range, enables the usage of the entire spectrum of sunlight. • The amplitude can reach tens of microns with high speed. [ABSTRACT FROM AUTHOR]

The micro-electromechanical-system (MEMS) force and acceleration sensor, based on the graphene-induced non-radiative transition, was investigated using analytical solution and finite element analysis methods. The graphene-induced non-radiative transition is highly sensitive to distance, and the deflection of the graphene ribbon is highly susceptible to applied force or acceleration. As a result, a high-sensitivity MEMS sensor was designed to detect the deflection of the graphene ribbon of 1 nm, the force of 0.1 pN, and the acceleration of 0.1 mg. The MEMS sensor, which has a size of only tens of microns, can be charged by light irradiation without connecting power sources. The generated signal can be detected from a long distance without an integrated radio reflection circuit. Therefore, it will have significant application prospects in the fields of micro-smart devices, wearable devices, biomedical systems, and so on. [Display omitted] • Graphene induced non-radiative transition is introduced into MEMS sensors. • The sensor can be charged by lighting, and can realize remote detection. • The sensor can detect forces of less than 0.1 pN and accelerations of less than 0.1 mg. • This size of sensor is only tens of microns. [ABSTRACT FROM AUTHOR]

In this paper, a facile method to synthesize two-dimensional (2D) all-inorganic CsPb 2 Br 5 nano-/micro-sheets at room temperature and their application as the active layer in solution-processed high-performance photodetectors are presented. The obtained CsPb 2 Br 5 nano-/micro-sheets showed a photoluminescence emission peak at 522 nm with a narrow full-width-at-half-maximum of ∼17 nm, showing its high color purity, and an absorption peak at 307 nm with a shoulder peak at 339 nm. Then, the obtained CsPb 2 Br 5 nano-/micro-sheets were used as the active layer in photoconductive photodetector and a high specific detectivity of 1.0 × 1012 Jones with a photoresponsivity of 0.02 A/W and an ultra-low dark current of ∼10−12 An under 16 μW/cm2 405 nm illumination were obtained from photoconductive photodetector Au/CsPb 2 Br 5 (85 μm)/Au. Further, the physical mechanism for the enhanced performance is discussed. Therefore, it provides a new method to suppress dark current for high-performance CsPb 2 Br 5 photodetectors. • A new synthesis method for CsPb 2 Br 5 nano-/micro-sheets is presented. • A facile and ligand-free scheme was employed for CsPb 2 Br 5 nano-/micro-sheets. • Photodetectors based on CsPb 2 Br 5 nano-/micro-sheets showed high performance. • The enhanced device performance is mainly due to the suppressed dark current. [ABSTRACT FROM AUTHOR]

Interface modifying between the active layer and anode solar cells is a key technique to improve the device performance. In this paper, the enhancement of power conversion efficiency (PCE) of ZnO/PbS heterojunction quantum dot (QD) solar cells Au/PbS-TBAI/ZnO/ITO was achieved by incorporating a graphene oxide (GO) layer between the PbS-TBAI active film and the Au anode. Our experimental data showed the GO interlayer was partially reduced to graphene after its post-annealing at 140 °C and it played the role of hole-transporting layer and the interface-modifying layer. In this way, the defects existed at the contact interface of PbS-TBAI/Au were reduced significantly after inserting and post-annealing GO interlayer, resulting to the enhancement of holes transport and collection efficiency, showing a PCE enhancement of 12.87% as compared to that of the control device Au/PbS-TBAI/ZnO/ITO. The influence of post-annealing treatment on the whole device, as the reduction method for GO, on the performance of the QD solar cells was also explored and discussed. [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]

Two novel tetradentate platinum (II) 3,6-substituted salophen complexes of Pt-2 and Pt-3 were synthesized and characterized, in which the substituted group is a donor (D) unit of 4,4′-di( tert -butyl)triphenylamine (Bu t TPA) for Pt-2 and a donor-acceptor (D-A) framework of Bu t TPA and benzothiadiazole (BT) for Pt-3. Their thermal, optophysical, electrochemical and electroluminescent properties were primarily investigated. It is found that the emission for this type of tetradentate platinum (II) complexes is tuned from deep red to near infrared by appending D-A framework under photo-excitation. As a result, Pt-3 presented a significant near infrared electroluminescence peaked at 703 nm in its doped polymer light-emitting devices (PLEDs). The maximum external quantum efficiency of 0.88% is observed in the Pt-3 doped PLEDs using a blend of poly(vinylcarbazole) and 1,3-bis(5-(4-( tert -butyl)phenyl)-1,3,4-oxadiazol-2-yl) benzene as the host matrix. Our work indicates that appending D-A framework into tetradentate Pt(II) salophen complex is a useful strategy to get high-performance near infrared emission for this type of tetradentate Pt (II) complexes. [ABSTRACT FROM AUTHOR]

Two novel tetradentate bis-cyclometalated platinum (IV) complexes of TPA-2q-PtCl 2 and 3TPA-2q-PtCl 2 with C ˆ N*N ˆ C cyclometalated ligands and two coordinated chlorine atoms were synthesized and characterized. The crystal structure of TPA-2q-PtCl 2 shows a trans -form irregular octahedral geometry by measurement of single-crystal X-ray diffraction, where two C ˆ N coordination moieties are twisted and two chlorine atoms are located on both sides of platinum atom. A medium absorption band in a range of 450–474 nm is observed, which is assigned to the metal-to-ligand charge-transfer (MLCT) and intramolecular charge transfer (ILCT). And two obvious emission peaks at about 635 and 750 nm are displayed for both platinum (IV) complexes in 2-methyltetrahydrofuran solutions, which originate from the ILCT and MLCT characters to the lowest excited state. Using one of platinum (IV) complexes as a single dopant and a blend of poly(vinylcarbazole) as a host matrix, their single-emissive-layer polymer light-emitting diodes (PLEDs) exhibit an outstanding near-infrared emission with an electroluminescent (EL) peak of 750 nm. The better electroluminescent properties are obtained in the 3TPA-2q-PtCl 2 doped devices with an external quantum efficiency of 0.85% and a radiance of 164 μW/cm −2 . This is the first reported sample about tetradentate biscyclometalated platinum (IV) complexes used as organic NIR electroluminescent materials for promising application in PLEDs. [ABSTRACT FROM AUTHOR]

Two novel tetradentate platinum (II) salophen complexes A and B, respectively substituted by dual donor-accepter frameworks of phenazine-triphenylamine in the heads and waists of salophen, were synthesized and characterized. By changing the substituted positions of dual phenazine-triphenylamine units, different optophysical, electrochemical and electroluminescent properties were remarkably observed for the both platinum (II) salophen complexes. Using a blend of poly(vinyl-carbazole) (PVK) and 1,3-bis(5-(4-( tert -butyl) phenyl)-1,3,4-oxadiazol-2-yl)benzene (OXD-7) as host matrix, the platinum (II) salophen complexes A and B exhibited a deep red emission at 653 nm and a near-infrared (NIR) emission at 695 nm in the single-emissive-layer polymer light-emitting devices, respectively. The maximum external quantum efficiency ( EQE ) of 1.36% and highest radiant intensity ( R ) of 45 μ W cm −2 were obtained in the complex B-doped devices, which are 13.6 and 2.6 times of those corresponding values in the complex A-doped devices. It indicates that appending dual donor-accepter frameworks in the heads of salophen is an efficient strategy to achieve NIR emission for their tetradentate platinum (II) complexes. [ABSTRACT FROM AUTHOR]

The image quality of the reflective zoom system is strongly reduced when the position of the mirror is changed during the zooming process. A new alignment method based on vector wavefront aberration theory is suggested in order to surmount this problem during the zoom process. During the three-mirror reflective zoom system zooming process, the secondary mirror plays an active role and the tertiary mirror plays a complementary role. This feature enables adjustment of the tertiary mirror to compensate for the misalignment of the secondary mirror in the zoom process. The alignment of a three-mirror reflective zoom system was simulated. First, we imposed a feeble maladjustment on the secondary mirror as its position was changed during the zooming process. Then, we obtained the compensation values for the tertiary mirror by using the vector wavefront aberration theory. Lastly, the compensation values were imported to be applied to a misaligned three-mirror reflective zoom system. The image quality of the zoom system prior to and after the application of our proposed alignment method validates its correctness and viability. [ABSTRACT FROM AUTHOR]