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Effects of the film thickness and poling electric field on photovoltaic performances of (Pb,La)(Zr,Ti)O3 ferroelectric thin film-based devices
摘要： The ferroelectric photovoltaic (FPV) effect obtained in inorganic perovskite ferroelectric materials has received much attention because of its large potential in preparing FPV devices with superior stability, high open-circuit voltage (Voc) and large short-circuit current density (Jsc). In order to obtain suitable thickness for the ferroelectric thin film as light absorption layer, in which, the sunlight can be fully absorbed and the photo-generated electrons and holes are recombined as few as possible, we prepare Pb0.93La0.07(Zr0.6Ti0.4)0.9825O3 (PLZT) ferroelectric thin films with different layer numbers by the sol-gel method and based on these thin films, obtain FPV devices with FTO/PLZT/Au structure. By measuring photovoltaic properties, it is found that the device with 4 layer-PLZT thin film (~300 nm thickness) exhibits the largest Voc and Jsc and the photovoltaic effect obviously depends on the value and direction of the poling electric field. When the device is applied a negative poling electric field, both the Voc and Jsc are significantly higher than those of the device applied the positive poling electric field, due to the depolarization field resulting from the remnant polarization in the same direction with the built-in electric field induced by the Schottky barrier, and the higher the negative poling electric field, the larger the Voc and Jsc. At a -333 kV/cm poling electric field, the FPV device exhibits the most superior photovoltaic properties with a Voc of as high as 0.73 V and Jsc of as large as 2.11 μA/cm2. This work opens a new way for developing ferroelectric photovoltaic devices with good properties.
关键词： Film thickness,Ferroelectric thin film,Ferroelectric photovoltaic devices,Depolarized electric field,Inorganic perovskite
更新于2025-09-16 10:30:52
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Improving Output Power of InGaN Laser Diode Using Asymmetric In0.15Ga0.85N/In0.02Ga0.98N Multiple Quantum Wells
摘要： Herein, the optical ?eld distribution and electrical property improvements of the InGaN laser diode with an emission wavelength around 416 nm are theoretically investigated by adjusting the relative thickness of the ?rst or last barrier layer in the three In0.15Ga0.85N/In0.02Ga0.98N quantum wells, which is achieved with the simulation program Crosslight. It was found that the thickness of the ?rst or last InGaN barrier has strong e?ects on the threshold currents and output powers of the laser diodes. The optimal thickness of the ?rst quantum barrier layer (FQB) and last quantum barrier layer (LQB) were found to be 225 nm and 300 nm, respectively. The thickness of LQB layer predominantly a?ects the output power compared to that of the FQB layer, and the highest output power achieved 3.87 times that of the reference structure (symmetric quantum well), which is attributed to reduced optical absorption loss as well as the reduced vertical electron leakage current leaking from the quantum wells to the p-type region. Our result proves that an appropriate LQB layer thickness is advantageous for achieving low threshold current and high output power lasers.
关键词： asymmetric multiple quantum wells,optical absorption loss,InGaN laser diodes,barrier thickness,electron leakage current
更新于2025-09-16 10:30:52
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Features of Laser Welding Light Constructions from Cryogenic Austenitic Steel 316L
摘要： The publication describes the results of the research of the influence of laser welding mode parameters on geometry and quality of the formation of the welded joint of 316L steel with thickness of 1 mm. According to the results of research in the framework of pre-project works, in order to test the technology at the real objects, components of light metal structures were welded.
关键词： metal with thin thickness,light construction,austenitic steel 316L,laser welding
更新于2025-09-16 10:30:52
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The Studies of Plasma Torch Processes by Laser Beam Welding
摘要： The manufacturing of significant products with help of laser beam welding technologies requires higher stability characteristics of such technologies; this explains the necessity to run on-line testing procedures of through pro-melting process. This type of testing can be carried out by the registration of plasma streams that occur under a work piece by through pro-melting [i.e. metal undergoes an intensive laser beam thermal processing].
关键词： collectors of charged particles,plasma,informational-measuring system,plasma torch,analog-to-digital converter,ionization of metal vapor,welding of small thickness products,laser beam welding,through pro-melting
更新于2025-09-16 10:30:52
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Illustrating the Shell Thickness Dependence in Alloyed Core/Shell Quantum Dot based Light-Emitting Diodes by Impedance Spectroscopy
摘要： Colloidal quantum dots (QDs) are talented materials and have been extensively investigated in the field of photonics and optoelectronics due to their size-dependent optical properties. The core/shell structure of QDs with wide bandgap shell has been adopted for obtaining stable emission and high PL quantum efficiency. However, when employed in active devices such as light-emitting diodes (LEDs), the thick shell structure of QDs may impede the transportation of carriers thus deteriorate the device performance. In this work, the effect of shell thickness of CdSe/ZnS QDs on device performance is systematically studied through impedance spectroscopy (IS) by constructing the electron-only symmetric device architecture. It is found that the evolution of capacitance in the symmetric device under applied voltage reflects the charge accumulation within the device and predicts the LED performance. The lowest capacitance is evaluated in the symmetric device containing QDs with a medium shell size of 2.1 nm, showing improved performance in LED with the highest luminance and current efficiency (CE) of 26370 cd/m2 and 8.3 cd/A respectively.
关键词： impedance spectroscopy,light-emitting diodes,charge accumulation,shell thickness,Colloidal quantum dots
更新于2025-09-16 10:30:52
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Effects of Active layer thickness on optical properties of polymer OLEDs
摘要： We have proposed and described precisely remarkable improvements of emitted power and corresponding optical parameters of Indium Tin Oxide (ITO)/Emissive Layer (EL)/Electron Transport Layer (ETL)/Aluminum based Organic Light Emitting Diode (OLED). Changing EL thickness we perceived the emitted power, although maximum emissive power (18.4 mW/ m2-nm -S) is obtained at approximate 490 nm wavelength for 60 nm EL, along with observed recombination rate, exciton density, electric field and carrier density. Bilayer OLED is simulated in which active layer is EL by using BAlq [Bis(2-methyl-8- quinolinolate)-4- (phenylphenolato) Aluminum] polymer and other is ETL by using Alq [tris(8-hydroxyquinoline) aluminum] polymer between two electrodes anode (ITO) and cathode (Al).
关键词： Polymer OLED,Electron transport layer,Tradeoff,Thickness of EL,Emissive layer
更新于2025-09-16 10:30:52
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Roll-to-roll printed stable and thickness-independent ZnO:PEI composite electron transport layer for inverted organic solar cells
摘要： Large-scale roll-to-roll (R2R) micro-gravure printing is one of the most e?ective fabrication techniques to achieve the commercialization of organic solar cells (OSCs). In the high-performance OSC devices, the electron transport layer (ETL) plays an important role. In this paper, a composite ink of ZnO and polyethylenimine (PEI) was developed to fabricate large-area ETL for the inverted OSCs through R2R micro-gravure printing. It was found that the modi?cation of ZnO nanoparticles by PEI e?ectively improved ink stability and enhanced the mechanical property. Using R2R micro-gravure printing, the thickness and coverage of the ZnO: PEI ?lms were well regulated through changing the printing roller speed and web speed. Consequently, a high-power conversion e?ciency around 6% was obtained for the ?exible PTB7-Th: PC71BM device with the thickness of R2R printed ZnO: PEI layer up to 120 nm, demonstrating the high printability of this ZnO: PEI composite material for the use in printed ?exible OSCs as the interface layer.
关键词： Organic solar cells,Roll-to-roll printing,Thickness-independent,Long-term stability,ZnO: PEI composite materials
更新于2025-09-16 10:30:52
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Efficient non-fullerene organic solar cells based on thickness-insensitive conjugated small molecule cathode interface
摘要： Interfacial engineering plays an essential role in the enhancement of device performance of organic solar cells (OSCs). Plentiful dopant-free electron- transporting materials have been e?ectively applied to modify ZnO in the inverted OSCs. However, these materials usually work with strict thickness, which observably limits their application in large area device fabrication. In this manuscript, an industrial small-molecule PyM with simply chemical structure solved in methyl alcohol was applied to modify ZnO in non-fullerene OSCs. PyM has good solubility in both methyl alcohol and chlorobenzene. Therefore, there is only a thin PyM layer left and distributed on the ZnO surface after coating the active layer. Meanwhile, a small amount PyM may be blended with the active layer near ZnO layer. The intense interaction between ZnO and PyM layer as well as the potential n-doping between PyM and the electron acceptor could modify the work function of ZnO and reduce the charge carrier recombination. Correspondingly, the inverted PBDB-T:ITIC OSCs with ZnO/PyM serving as electron transport layers achieve device power conversion e?ciency (PCE) of 10.9% and 10.0% with 10 nm and 105 nm thick PyM ?lm, respectively. The device performance is insensitive to the thickness of PyM. This phenomenon indicates that the PyM can be employed in roll-to-roll techniques to fabricate large-area devices at low cost. Similar results also emerged in PBDB-T:IT-M system, and the PCE was improved from 10.4% to 11.5% for ZnO and ZnO/PyM (~10 nm)-based devices.
关键词： Cathode interface,Organic solar cells,Hydrophobic property,Non-fullerene,Hydrogen bond,Thickness-insensitive
更新于2025-09-16 10:30:52
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The Effect of ALD-Zn(O,S) Buffer Layer on the Performance of CIGSSe Thin Film Solar Cells
摘要： In this paper, we report the development of Cd-free bu?ers using atomic layer deposition (ALD) for Cu(In,Ga)(S,Se)2-based solar cells. The ALD process gives good control of thickness and the S/S +O ratio content of the ?lms. The in?uence of the growth per cycle (GPC) and the S/(S+O) ratio, and the glass temperature of the atomic layer deposited Zn(O,S) bu?er layers on the e?ciency of the Cu(In,Ga)(S,Se)2 solar cells were investigated. We present the ?rst results from our work on cadmium-free CIGS solar cells on substrates with an aperture area of 0.4 cm2. These Zn(O,S) layers were deposited by atomic layer deposition at 120?C with S/Zn ratios of 0.7, and layers of around 30 nm. The Zn(O,S) 20% (Pulse Ratio: H2S/H2O+H2S) process results in a S/Zn ratio of 0.7. We achieved independently certi?ed aperture area e?ciencies of 17.1% for 0.4 cm2 cells.
关键词： atomic layer deposition,Zn(O,S) thickness,Cu(In,Ga)(S,Se)2 absorber layer,Zn(O,S) ratio,Zn(O,S) temperature window,bu?er layer,solar cell
更新于2025-09-16 10:30:52
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Ocular Aberrations and Corneal Thickness-Intraocular Pressure Relationship One Year after Laser in situ Keratomileusis (LASIK) Enhancement with An Aspheric Ablation Profile
摘要： Objective: To evaluate the effect of an aspheric LASIK refractive enhancement performed by relifting the original flap on the higher order aberrations (HOA) of the eye and the relationship between central corneal thickness (CCT) and intra-ocular pressure (IOP). Methods: Consecutive case series of 30 eyes requiring refractive enhancement from 1804 uncomplicated primary LASIK procedures performed in 2012. Flap relift and wavefront optimized ablation (Wavelight Allegretto Eye Q 400 Hz excimer laser) were performed in all cases. Pre-and post-operative examination included Shack-Hartmann aberrometry for 3 mm and 5 mm pupil sizes, CCT and IOP. Postoperative results at 1 year were compared to baseline values. Results: Changes in average values of coma, spherical aberration (SA), trefoil, CCT and IOP were not significant. Linear regression revealed significant associations between change (y) in trefoil and pre-enhancement value of trefoil for 3 mm pupil (0.828x-0.045, r=0.722, p<0.001), coma and pre-enhancement value of coma for 5 mm pupil (y=0.281x-0.030, r=0.501, n=30, p=0.048), SA for 3 mm pupil compared with change in CT (y=0.0080-0.0009x, r=-0.378, p=0.0392), and SA for 5 mm pupil compared with change in CCT (y=0.0035x-0.0541, r=0.524, p=0.0029). Also there was a significant association between IOP and CCT both pre-(IOP=0.0313CT-3.3, r=0.740, p<0.0001) and post-enhancement (IOP=0.0243CT-0.018, r=0.675, p<0.0001). Conclusion: LASIK enhancement with an aspheric ablation profile did not significantly impact on the average values for HOAs, IOP or CCT. For individual cases, the likely shift in magnitude of coma, trefoil and SA can be estimated and, the change in SA is correlated with changes in CCT. The change in the abscissa value linking IOP with CCT may be an indication of changes in biomechanical properties of the cornea in the central region.
关键词： High order aberrations (Hoas),LASIK enhancement,Wavefront,Intraocular pressure (IOP),Excimer laser,Wavelight allegretto,Corneal thickness
更新于2025-09-16 10:30:52