In this study, we synthesized a series
of small-molecule benzotrithiophenes
(BTTs) and used them as hole transporting materials (HTMs) in perovskite
solar cells (PSCs). The asymmetric benzo[2,1-b:-3,4-b′:5,6-b″]trithiophene unit
was used as the central core to which were appended various donor
groups, namely, carbazole (BTT-CB), thieno thiophene (BTT-FT), triphenylamine
(BTT-TPA), and bithiophene (BTT-TT). The extended aromatic core in
the asymmetric BTT provided full planarity, thereby favoring intermolecular
π-stacking and charge transport. The physical, optical, and
electrical properties of these small-molecule HTMs are reported herein.
BTT-TT displayed good crystallinity and superior hole mobility, when
compared with those of the other three HTMs, and formed smooth and
uniform surfaces when covering the perovskite active layer. Accordingly,
among the devices prepared in this study, a PSC incorporating BTT-TT
as the HTM achieved the highest power conversion efficiency (18.58%).
Moreover, this BTT-TT-containing device exhibited good stability after
storage for more than 700 h. Thus, asymmetric BTTs are promising candidate
materials for use as small-molecule HTMs in PSCs.
The adsorption equilibrium and kinetics of polyethylene glycol (PEG) in three aqueous systems were examined in this study. Langmuir isotherm was used to satisfactorily predict the adsorption capacity of PEG on activated carbon F-400 and applied to the investigation of adsorption kinetics. The surface diffusion, pore diffusion, and branched pore kinetics models successfully described the adsorption behavior of PEG on F-400 in the completely stirred tank reactor. The pore diffusion coefficients obtained from the pore diffusion model were compared with those computed by the experimental data of the short fixed-bed reactor combined with the assumption of non-hindered pore diffusion. In addition, the effects of initial concentrations of PEG and the relative importance of external and internal mass transfers for the adsorption were also taken into account and discussed in this study.
Polynuclear aromatic hydrocarbons (PAHs), which are environmental hormones and carcinogens, are viewed as the priority pollutants to deal with by many countries. Most PAHs are hydrophobic with high boiling and melting points and high electrochemical stability, but with low water solubility. Compared with other PAH species, naphthalene has less toxicity and is easily found in the environment. Thus, naphthalene is usually adopted as a model compound to examine the environmental and health aspects of PAHs. This study attempted to use an adsorption process to remove naphthalene from a water environment. The adsorption equilibrium of naphthalene on zeolite from water-butanol solution, which is a surfactant-enriched scrubbing liquid, was successfully evaluated by Langmuir, Freundlich, and linear isotherms. Among the tested kinetics models in this study (e.g., pseudo-first-order, pseudo-second-order, and Elovich rate equations), the pseudo-second-order equation successfully predicted the adsorption.
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