Investigation of Triple Symmetric Non-halogen Benzene Derivative Solvent for Spray-Coated Polymer Solar Cells.

The performance of spray-coated polymer solar cells could be largely improved via morphologies and phase optimization by solvent engineering. However, there is still a lack of fundamental knowledge and know-how in controlling blend morphology by using various solvents. Here, the effect of adding low polar benzene and non-halogen benzene derivatives with triple symmetric molecular has been systematically investigated and discussed. It is found that the triple symmetric non-halogen benzene could promote the formation of preferential face-on molecule orientation for PBDB-T-2Cl:IT4F films by grazing incidence wide-angle X-ray scattering. The X-ray photoelectron spectroscopy shows that PBDB-T-2Cl could be transported to the surface of the blend film during drying process. A 3D opt-digital microscope shows that triple symmetric non-halogen benzene could also improve the morphologies of active layers by reducing the coffee ring or other micro-defects. Due to the appropriate vapor pressures, devices with mixing 20% benzene or the triple symmetric non-halogen in spray solution could significantly improve the device performance. Device prepared using 20% 1,3,5-trimethylbenzene (TMB) and 80% chlorobenzene (CB) mixture solvent has the best morphology and phase structure, and the power conversion efficiency (PCE) of the device was increased nearly 60 to 10.21% compared with the device using CB as the only solvent.

Preparation of Monodispersed Cs0.33WO3 Nanocrystals by Mist Chemical Vapor Deposition for Near-Infrared Shielding Application.

In this study, single-phase Cs0.33WO3 nanocrystals were synthesized by a novel mist chemical vapor deposition method. As prepared, Cs0.33WO3 nanocrystals exhibited a microsphere-like appearance constructed with angular crystal grains with an average size of about 30-40 nm. Characterization by X-ray photoelectron spectroscopy indicated that Cs0.33WO3 nanocrystals consisted of mixed chemical valence states of tungsten ions W6+ and W5+, inducing many free electrons, which could scatter and absorb near-infrared (NIR) photons by plasmon resonance. These Cs0.33WO3 microspheres consisted of a loose structure that could be crushed to nanoscale particles and was easily applied for producing long-term stable ink after milling. Herein, a Cs0.33WO3/polymer composite was successfully fabricated via the ultrasonic spray coating method using mixed Cs0.33WO3 ink and polyurethane acrylate solution. The composite coatings exhibited excellent IR shielding properties. Remarkably, only 0.9 mg cm-2 Cs0.33WO3 could shield more than 70% of NIR, while still maintaining the visible light transmittance higher than 75%. Actual measurement results indicate that it has really good heat insulation properties and shows good prospect in heat insulation window applications.