Indium-doped perovskite-related cesium copper halide scintillator films for high-performance X-ray imaging

Scintillators are widely utilized in high-energy radiation detection in view of their high light yield and short fluorescence decay time.However,constrained by their current shortcomings,such as complex fabrication procedures,high temperature,and difficulty in the large scale,it is difficult to meet the increasing demand for costeffective,flexible,and environment-friendly X-ray detection using traditional scintillators.Perovskite-related cesium copper halide scintillators have recently received multitudinous research due to their tunable emission wavelength,high photoluminescence quantum yield(PLQY),and excellent optical properties.Herein,we demonstrated a facile solution-synthesis route for indium-doped all-inorganic cesium copper iodide(Cs_(3)Cu_(2)I_(5))powders and a high scintillation yield flexible film utilizing indium-doped Cs_(3)Cu_(2)I_(5)powders.The large area flexible films achieved a PLQY as high as 90.2%by appropriately adjusting the indium doping concentration,much higher than the undoped one(73.9%).Moreover,benefiting from low self-absorption and high PLQY,the Cs_(3)Cu_(2)I_(5):In films exhibited ultralow detection limit of 56.2 n Gy/s,high spatial resolution up to 11.3 lp/mm,and marvelous relative light output with strong stability,facilitating that Cs_(3)Cu_(2)I_(5):In films are excellent candidates for X-ray medical radiography.Our work provides an effective strategy for developing environment-friendly,low-cost,and efficient scintillator films,showing great potential in the application of highperformance X-ray imaging.

Review on flexible perovskite photodetector:processing and

Next-generation optoelectronics should possess lightweight and flexible characteristics,thus conforming to various types of surfaces or human skins for portable and wearable applications.Flexible photodetectors as fundamental devices have been receiving increasing attention owing to their potential applications in artificial intelligence,aerospace industry,and wise information technology of 120,among which perovskite is a promising candidate as the light-harvesting material for its outstanding optical and electrical properties,remarkable mechanical flexibility,low-cost and low-temperature processing methods.To date,most of the reports have demonstrated the fabrication methods of the perovskite materials,materials engineering,applications in solar cells,light-emitting diodes,lasers,and photodetectors,strategies for device performance enhancement,few can be seen with a focus on the processing strategies of perovskite-based flexible photodetectors,which we will give a comprehensive summary,herein.To begin with,a brief introduction to the fabrication methods of perovskite(solution and vapor-based methods),device configurations(photovoltaic,photoconductor,and phototransistor),and performance parameters of the perovskite-based photodetectors are first arranged.Emphatically,processing strategies for photodetectors are presented following,including flexible substrates(i.e.,polymer,carbon cloth,fiber,paper,etc.),soft electrodes(i.e.,metal-based conductive networks,carbon-based conductive materials,and two-dimensional(2D)conductive materials,etc.),conformal encapsulation(single-layer and multilayer stacked encapsulation),low-dimensional perovskites(0D,1D,and 2D nanostructures),and elaborate device structures.Typical applications of perovskite-based flexible photodetectors such as optical communication,image sensing,and health monitoring are further exhibited to learn the flexible photodetectors on a deeper level.Challenges and future research directions of perovskite-based flexible photodetectors are proposed in the end.The purpose of this review is not only to shed light on the basic design principle of flexible photodetectors,but also to serve as the roadmap for further developments of flexible photodetectors and exploring their applications in the fields of industrial manufacturing,human life,and health care.

Organic Passivation of Deep Defects in Cu(In,Ga)Se_(2) Film for Geometry-Simplified Compound Solar Cells

Diverse defects in copper indium gallium diselenide solar cells cause nonradiative recombination losses and impair device performance.Here,an organic passivation scheme for surface and grain boundary defects is reported,which employs an organic passivation agent to infiltrate the copper indium gallium diselenide thin films.A transparent conductive passivating(TCP)film is then developed by incorporating metal nanowires into the organic polymer and used in solar cells.The TCP films have a transmittance of more than 90%in the visible and nearinfrared spectra and a sheet resistance of~10.5Ω/sq.This leads to improvements in the open-circuit voltage and the efficiency of the organic passivated solar cells compared with control cells and paves the way for novel approaches to copper indium gallium diselenide defect passivation and possibly other compound solar cells.

Implementation of 1.7 kV Silicon Carbide Metal Oxide Semiconductor Field Effect Transistors in Auxiliary Power Supplies for Industrial Applications

An auxiliary power supply(Aux-PS)has become an essential component of electronic equipment for many industrial applications,such as in motor drives,photovoltaic(PV)inverters,uninterruptible power supply(UPS)systems and modular multilevel converters.The introduction of 1700 V silicon carbide(SiC)metal oxide semiconductor field effect transistors(MOSFETs)is useful for such applications,providing benefits with respect to a low on-state resistance,smaller package,low switching loss and single-switching implementation.A single end flyback Aux-PS is designed for industrial applications with a wide input voltage range using 1.7 kV SiC MOSFETs.The special design tradeoffs involved in the usage of SiC MOSFETs are discussed in detail,such as those with regard to gate driving voltage selection,isolation transformer design considerations,and clamping circuit design details.A 60 W demonstration hardware is developed and tested under different working conditions.The results verify the higher efficiency and better thermal performance of the proposed hardware relative to those of traditional Si solutions.

On the Understandings of Dielectric Constant and Its Impacts on the Photovoltaic Efficiency in Organic Solar Cells

Dielectric constant(ε)is an important parameter affecting the power conversion efficiency of organic solar cells(OSC).Increasingεof bulk heterojunctions in general can benefit the performance of OSCs,as an increasedεwill reduce the influence of Coulomb interaction between weakly bound electron-hole pairs on charge-transfer states or bimolecular recombination involving mobile carriers to reduce geminate and nongeminate losses.In this review,we overview the current understandings on dielectric constant and its impacts on exciton dissociation and voltage losses in OSCs and summarize recent efforts attempting to modify the dielectric properties of OSC materials through synthetic approaches.We further discuss the commonly adopted techniques for determining the parameter ofεwith stressing the testing conditions that may affect the accuracy of results.At last,we suggest that novel experimental methods to improve the dielectric constant and resultant physical processes in OSCs will be appreciated,which helps enrich the existing strategy reservoir toward enhancement of photovoltaic efficiencies.

Molecular dispersion enhances photovoltaic efficiency and thermal stability in quasi-bilayer organic solar cells

In comparison to widely adopted bulk heterojunction(BHJ)structures for organic solar cells(OSC),exploiting the sequential deposition to form planar heterojunction(PHJ)structures enables to realize the favorable vertical phase separation to facilitate charge extraction and reduce charge recombination in OSCs.However,effective tunings on the power conversion efficiency(PCE)in PHJ-OSCs are still restrained by the currently available methods.Based on a polymeric donor PBDBT-2 F(PBDBT=Poly[[4,8-bis[5-(2-ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl]-2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4 H,8 H-benzo[1,2-c:4,5-c′]dithiophene-1,3-diyl]-2,5-thiophenediyl])and a non-fullerene(NF)acceptor Y6,we proposed a strategy to improve the properties of photovoltaic performances in PHJ-based OSCs through dilute dispersions of the PBDBT-2 F donor into the acceptor-dominant phase with the sequential film deposition.With the control of donor dispersions,the charge transport balance in the PHJ-OSCs is improved,leading to the expedited photocarrier sweep-out with reduced bimolecular charge recombination.As a result,a PCE of 15.4%is achieved in the PHJ-OSCs.Importantly,the PHJ solar cells with donor dispersions exhibit better thermal stability than corresponding BHJ devices,which is related to the better film morphology robustness and less affected charge sweep-out during the thermal aging.