Effects of Donor and Acceptor on Optoelectronic Performance for Porphyrin Derivatives： Nonlinear Optical Properties and Dye-sensitized Solar Cells

Typical asymmetric donor-π-bridge-acceptor（D-π-A） zinc porphyrin dyes have been synthesized, and fur- ther modified by reacting the ethynyl groups of them with click reagent through a formal [2＋2] click reaction. The electronic interaction between the push and pull electronic groups and the click reaction process were investigated by UV-Vis absorption spectroscopy. The nonlinear optical（NLO） properties of the dyes were studied by the Z-scan tech- nique and clearly reverse saturable absorption to saturable absorption（RSA-SA） transition could be observed through click reaction of the dyes with TCNE. Furthermore, the photovoltaic properties of these porphyrin dyes were reaso- nably explained by the J-V curve fitting based on the equivalent-circuit model as well as the comparison between the absorption and incident-photon-to-current-conversion efficiency（IPCE） spectra. Besides, these dyes with different donors or acceptors could self-assembly into different microstructures by phase transfer methodology. Keywords Porphyrin derivative; Click chemistry; Optoelectronic performance; Nonlinear optical property; Dye-sensitized solar cell

Few-layer WSe2 lateral homo-and hetero-junctions with superior optoelectronic performance by laser manufacturing

Lateral hetero-junctions are considered as potential candidate for building blocks in modern electronics and optoelectronics,however,the construction of which remains a challenge.In this work,by using a laser-assisted manufacture technique,WSe2/WO3-x hetero-junction and monolayer/trilayer WSe2 homo-junction with Schottky diode like behavior are fabricated,both of which present competitive performance for photodetection and power generation in a wide range of wavelengths from ultraviolet to infrared,with maximum photoresponsivity of 10 A/W,external quantum efficiency of 14%,and power conversion efficiency of 1.3%.Combined with Kelvin probe microscopy and electrical transport measurements,it is demonstrated that the barrier-induced built-in electric field at WSe2/WO3-x interface,and the energy band discontinuities at the monolayer/trilayer WSe2 interface facilitate the separation of photo-generated electron-hole pairs.Our work provides a solid step towards the controllable construction of lateral junctions by laser-assisted manufacture for exploiting van der Waals materials-based novel electronic and optoelectronic applications.

Effect of sputtering conditions on growth and properties of ZnO :Al films

Al-doped zinc oxide（AZO） films were deposited on glass substrates by mid-frequency magnetron sputtering. The effects of substrate rotation speed and target-substrate distance on the electrical, optical properties and microstructure and crystal structures of the resulting films were investigated by scanning electron microscopy（SEM）, atomic force microscopy（AFM）, X-ray diffraction（XRD）, spectrophotometer and Hall-effect measurement system, respectively. XRD results show that all AZO films exhibit a strong preferred c-axis orientation. However, the crystallinity of films decreases with the increase of substrate rotation speed, accompanying with the unbalanced grains grows. For the films prepared at different target-substrate distances, the uniform microstructure and morphology are observed. The highest carrier concentration of 5.9×1020 cm-3 and Hall mobility of 13.1 cm^2/（V·s） are obtained at substrate rotation speed of 0 and target-substrate distance of 7 cm. The results indicate that the structure and performances of the AZO films are strongly affected by substrate rotation speed.

Effect and Mechanism of Solvent Properties on Solution Behavior and Films Condensed State Structure for the Semi-rigid Conjugated Polymers

Solvents have an essential association with polymer solution behavior.However,few researches have been deeply done on this respect.In recent years,our research group focus on the study on effect of solvent properties on solution behavior and film condensed state structure for semi-rigid conjugated polymer up till to apply for optoelectronic device.Herein,influence of solvent properties including solubility of solvent,aromaticity,polarity and hydrogen bonds on semi-rigid polymer chain solution behavior,i.e.,single chain conformation,chain shape,size and chains aggregated density were studied by means of static/dynamic laser light scattering(DLS/SLS)and exponential law etc.Effect of solvent properties on condensed state structure of the semi-rigid conjugated polymer film was studied by UV absorption spectroscopy,PL spectroscopy and electron microscopy etc.The essential reasons for the influence were discovered and the mechanism was revealed.It was found that solution behavior with different solvent properties had an essential physical relationship with chains condensed state structure of the semi-rigid conjugated polymers.More importantly,there was a quantitative structure-activity relationship between solution and film.The key to this relationship depended on the interaction between solvent molecules and the semi-rigid conjugated polymer chains.This interaction could also affect optoelectronic devices performance.This study is of great significance to effectively control the condensed state structure of the semirigid conjugated polymers in the process of dynamic evolution from solutions to films.It not only enriches the knowledge and understanding of both semi-rigid conjugated polymer solution behaviors and film condensed state physics based on polymer physics,but also is meaningful to practical application for conjugated polymer and other traditional polymer systems.

Solution-Processed Monolayer Molecular Crystals:From Precise Preparation to Advanced Applications

Emerging monolayer molecular crystals(MMCs)have become prosperous in recent decades due to their numerous advantages.First,downsizing the active layer thickness to monolayer in organic field-effect transistors(OFETs)is beneficial to elucidate the intrinsic charge-transport behavior.Next,the ultrathin conducting channel can reduce bulk injection resistance to extract mobility accurately.Then,direct exposure of the conducting channel can enhance the sensing performance.Finally,MMCs combine the merits of ultrathin thickness and high crystallization,which will improve the optoelectronic performance and realize complex device architectures for future advanced optoelectronic applications.In this Review,recent research progress in precise preparations and advanced applications of solution-processed MMCs are summarized.We present the current challenges related to MMCs with specific structures and desired performances,and an outlook regarding their application in next-generation integrated organic optoelectronics is provided.