Condensation is a ubiquitous natural phenomenon with both detrimental and beneficial implications. The key point to minimize its harmful effects while harnessing its potential for various applications is the spatial controlling of condensation. In recent years, using hygroscopic liquids for spatially controlling condensation has gradually emerged as a promising strategy. However, the underlying mechanisms and influencing parameters of controlling condensation with hygroscopic liquids remain insufficiently understood. In this paper, the effect of hygroscopic droplets in suppressing condensation on low-temperature surfaces, specifically -15 ℃ to 15 ℃, under different conditions, including substrate temperature, cooling time, droplet volume are studied. A typical hygroscopic liquid, dipropylene glycol, was employed to illustrate this issue. The results indicated that distinct ring-shaped dry zone forms around dipropylene glycol droplets on low-temperature surfaces, evidencing their efficacy in inhibiting condensation. Experiments and theoretical analysis reveal that the ratio of the dry-zone radius to the droplet radius is a function of substrate surface temperature, scaling as 1/( T dew - T c ). The results also show that cooling time has a negligible effect on this ratio over short periods. Furthermore, the ratio slightly decreases with increasing droplet volume at higher substrate temperatures, while remaining nearly constant at lower temperatures. These findings may enhance our understanding of the condensation inhibition effect of hygroscopic droplets and also provide valuable insights for potential applications in condensation control.
Guijun Zhang,Hua Peng,Qianwen Wei,Zheng Zhou,Haixia Wu,Jingjing Luo,Juan Wang,Xiaoming Wen,Yu Yang
The photoelectric characteristics of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) films significantly affect the power conversion efficiency and stability of Si/PEDOT:PSS hybrid solar cells. In this paper, we investigated PEDOT:PSS modification with alcohol ether solvents (dipropylene glycol methyl ether (DPM) and propylene glycol phenyl ether (PPH)). The reduction of PSS content and the transformation of the PEDOT chain from benzene to a quinone structure in PEDOT:PSS induced by doping with DPM or PPH are the reasons for the improved conductivity of PEDOT:PSS films. DPM and PPH doping improves the quality of silicon with the PEDOT:PSS heterojunction and silicon surface passivation, thereby reducing the surface recombination of charge carriers, which improves the photovoltaic performance of Si/PEDOT:PSS solar cells. Comparing the power conversion performance (PCE) and air stability of Si/PEDOT:PSS solar cells with DPM (13.24%), DPH (13.51%), ethylene glycol (EG, 13.07%), and dimethyl sulfoxide (DMSO, 12.62%), it is suggested that doping with DPM and DPH can replace DMSO and EG to enhance the performance of Si/PEDOT:PSS solar cells. The EG and DMSO solvents not only have a certain toxicity to the human body but also are not environmentally friendly. In comparison to DMSO and EG, DPM and DPH are more economical and environmentally friendly, helping to reduce the manufacturing cost of Si/PEDOT:PSS solar cells and making them more conducive to their commercial applications.
Cross-linked PMMA microspheres have been synthesized by photoinitiated RAFT dispersion polymerization with dipropylene glycol diacrylate (DPGDA) or trimethylolpropane triacrylate (TMPTA) as the cross-linker. Monodisperse microspheres were obtained in the presence of 0.5 wt% S,S′-bis(α,α′-dimethyl-α′′-acetic acid) trithiocarbonate (BDMAT, a RAFT agent) with DPGDA concentration up to 5 wt% or TMPTA concentration up to 2 wt%. The particle formation process was investigated, and the results reveal that the cross-linking reaction was retarded to a certain extent by the RAFT process, which is crucial for the formation of uniform particles under high cross-linker concentrations. The phase diagrams for the methodology have been built up, and show that the procedure could only give polydisperse microspheres at a low DPGDA concentration or coagulum at a high DPGDA concentration in the absence of a RAFT agent, and monodisperse microspheres were obtained at DPGDA concentration up to 5 wt% when the RAFT agent concentration reached an appropriately high level, e.g. 0.5 wt% BDMAT or 0.75 wt% DDMAT. By adjusting the reaction conditions, we have prepared monodisperse cross-linked PMMA microspheres with 10 wt% DPGDA added at the beginning of the reaction. Furthermore, we have functionalized the cross-linked microspheres by adding a functional comonomer to the system at the beginning of polymerization, or by surface-initiated RAFT polymerization via the RAFT groups attached on the particle surface.
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