Non-contact and non-destructive in-situ inspection for CdSe quantum dot film based on the principle of field-induced photoluminescence quenching

CdSe quantum-dot(QD)film,as the core function layer,plays a key role in various optoelectronic devices.The thickness uniformity of QD films is one of the key factors to determine the overall photoelectric performance.Therefore,it is important to obtain the thickness distribution of large-area QD films.However,it is difficult for traditional methods to quickly get the information related to its thickness distribution without introducing additional damage.In this paper,a non-contact and non-destructive inspection method for in-situ detecting the thickness uniformity of CdSe QD film is proposed.The principle behind this in-situ inspection method is that the photoluminescence quenching phenomenon of the QD film would occur under a high electric field,and the degree of photoluminescence quenching is related to the thickness of the quantum dot films.Photoluminescence images of the same QD film without and with an electric field are recorded by a charge-coupled device camera,respectively.By transforming the brightness distribution of these two images,we can intuitively see the thickness information of the thin film array of QD.The proposed method provides a meaningful inspection for the manufacture of QD based lightemitting display.

High performance IEICO-4F/WSe_(2)heterojunction photodetector based on photoluminescence quenching behavior

Heterostructure is the basic building block for functional optoelectronic devices.Heterostructures consisting of two-dimensional(2D)transition metal dichalcogenides(TMDs)and organic semiconductors are currently attracting great interest for highperformance optoelectronics.However,how to design heterostructure for highly efficient optoelectronic devices remains a big challenge.Here we design high-performance organic semiconductor/WSe_(2)heterostructure photodetectors by tailoring the charge transfer effect between 2,2ʹ-((2Z,2ʹZ)-(((4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydros-indaceno[1,2-b:5,6-bʹ]dithiophene-2,7-diyl)bis(4-((2-ethylhexyl)oxy)thiophene-5,2-diyl))bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile(IEICO-4F)organic semiconductors with various thicknesses and monolayer WSe_(2).With the increase of IEICO-4F layer thickness,the photoluminescence(PL)characteristics of WSe_(2)could be completely quenched due to the charge transfer from the lowest unoccupied molecular orbital(LUMO)level of IEICO-4F to the conduction band minimum(CBM)of WSe_(2).Benefiting from the exquisite charge transfer behavior,the IEICO-4F/WSe_(2)heterojunction photodetector with optimized 6.0-nm thick IEICO-4F shows high performance including the responsivity of 8.32 A/W and specific detectivity of 4.65×10^(11)Jones at incident light of 808 nm.This work demonstrates a simple approach based on PL characteristics to design high-performance IEICO-4F/WSe_(2)heterojunction,thus paving the way for the development of excellent optoelectronic devices based on organic/TMD heterostructures.

Electric field-induced photoluminescence quenching in Pr-doped BNT ceramics across the MPB region

Piezophotonics is a great interesting field of physics that has led to a number of important technologies,such as light source,smart sensors,and mechatronics.In this work,we reported Pr-doped(Bi_(0.5)Na_(0.5))TiO_(3)-based lead-free ceramics with strong red photoluminescence emission and large strain response(d_(33)^(*)=460 pm/V,S=0.32%).The PL emission can be quenched by decreasing the intensity by 93%after electrical polarization(E=50 kV/cm).The local structure and electric field-induced structural changes were systematically investigated to reveal the significant distinction in photoluminescence properties caused by electrical polarization.The results indicated that polarization treatment eliminates the structural inhomogeneities and establishes a long-range ferroelectric tetragonal and rhombohedral distortion.The crystal structure transformed irreversibly from a non-ergodic to a normal ferroelectric state.PL quenching originated from the decreased distortion of octahedral due to the transition from a non-ergodic state to a highly ordered symmetrical structure.Meanwhile,the enlarged domain structure contributed to the photoluminescence quenching effect.Our findings demonstrate that an electric field can be a robust tool for adjusting the photoluminescence property and provide insights into the rela-tionship between the structure and PL properties of BNT-based ceramics under an external stimulus.

Photoluminescence quenching of quantum-confined cadmium sulfide clusters by norbornadiene derivatives

Influence of norbornadiene and its derivatives on the photoluminescence (PL) of quantum-confined cadmium sulfide clusters (Q-CdS) prepared in reverse micelles wm investigated. It was found that norbornadiene-2,3-dicarboxylic acid (3) and its monopotassium salt (4) quenched PL intensity by 77% and 62%, respectively, whereas its dipotassium salt (a), norbornadiene (1) and norbornadiene-2,3-dimethylcarboxylate (2) had no effect on PL intensity. The formation constants for adducts formed between defect sites at the surface of Q-CdS clusters and 3 or 4 were also determined. PL quenching effect was attributed to the presence of ionizable proton which is considered to be able to trap photogenerated electrons and remove them from possible decay process. Measurements of the PL decay by single photon counting technique also supported these steady-state observations.

Synthesis and characterization of a novel main chain oxadiazole-based copolymer for n-type solar cell material

A novel oxadiazole-based copolymer has been successfully synthesized through the palladium-catalyzed cross-coupling polycondensation method. The copolymer P is soluble in common organic solvents. Its structure has characterized by ^1H NMR, ^13C NMR, gel permeation chromatagraphy （GPC）, UV-vis absorbance （Abs） and photoluniminescence （PL） spectroscopy, and cyclic voltammetry （CV）. Investigation of its optical properties revealed that it is yellow emitting material, and the electrochemical analysis showed that P was well suited poly （2,5-dioctyloxy-p-phenylenevinylene） （PDOCPV） for photovoltaic devices, so the copolymer P is able to act as an electron acceptor in combination with PDOCPVas the electron donor to quench photoluminescence of the copolymer in the blend, indicative of the efficient photoinduced electron transfer from the PDOCPV to the P.

Facile Preparation, Characterization of Flexible Organic Solar Cells Using P3HT-MWCNTS Composite Photoactive Layer

Multiwalled carbon nanotubes (MWCNTs) mixed in poly(3-hexylthiophene) (P3HT) were used as a photoactive layer for organic solar cells (OSC). The flexible OSCs of a structure of PET/rGO-P3HT/P3CT/PCBM/LiF-Al were prepared by spincoating. The UV-Vis absorption spectra of the photoactive films and current-voltage characteristics of the OSCs showed the advantage of the composite devices above the pristine-polymeric ones. Under illumination of light with a 100 mW/cm2-powerdensity, the photoelectrical conversion efficiency (PCE) of the OSCs with 3.0 wt% MWNCTs embedded in the photoactive layer possess a value as large as 2.35%. The obtained results suggest further useful applications of the flexible large-area solar cells.

Photogated proton conductivity of ZIF-8 membranes co-modified with graphene quantum dots and polystyrene sulfonate

Smart proton conductive metal-organic framework(MOF) membranes with dynamic remote control over proton conduction show high potential for use in advanced applications, such as sensors and bioprocesses. Here, we report a photoswitchable proton conductive ZIF-8 membrane by coencapsulating polystyrene sulfonate and graphene quantum dots into a ZIF-8 matrix(GQDs-PSS@ZIF-8) via a solidconfined conversion process. The proton conductivity of the GQDs-PSS@ZIF-8 membrane is 6.3 times higher than that of pristine ZIF-8 and can be reversibly switched by light due to photoluminescence quenching and the photothermal conversion effect, which converts light into heat. The local increase in temperature allows water molecules to escape from the porous channels, which cuts off the proton transport pathways and results in a decrease in proton conductivity. The proton conductivity is restored when the light is off owing to regaining water molecules, which act as proton carriers, from the surroundings. The GQDs-PSS@ZIF-8 membrane responds efficiently to light and exhibits an ON/OFF ratio of 12.8. This photogated proton conduction in MOFs has potential for the development and application of MOF-based protonic solids in advanced photoelectric devices.

Borophene-ZnO heterostructures:Preparation and application as broadband photonic nonvolatile memory

High-performance photonic nonvolatile memory which combines data storage and photosensing can achieve low power consumption and ensure computational energy efficiency.Heterostructure has been theoretically and experimentally proved to have synergistic effects between two materials,which can lead to promising electronic and optical properties for advanced optoelectronic devices.Herein,we report the preparation of borophene-ZnO heterostructures and their applications of broadband photonic nonvolatile memory.The memory shows a good switching ratio(5×10^(3))and long-term stability(3,600 s),which are superior to those of the pristine borophene or ZnO quantum dots(QDs).It is found that the memory shows a broad light response from ultraviolet(365 nm)to near infrared(850 nm).Besides,the SET voltage will decrease when the device is exposed to light,which can be attributed to the separation of holes and electrons in accelerating the formation of vacancy conductive filament.This work not only provides a promising material for next-generation photoelectric information,but also paves the way for borophene-based memory towards data storage devices.