Hole-transporting material (HTM) is an indispensable constituent in organic electronic devices, generally comprising a donor/dopant combination. We report that a disodium salt of substituted benzo[1,2- b:4,5- b']dipyrrole bearing two racemic alkanediylsulfonate anion side chains (BDPSOs) serves as a neutral, nonhygroscopic, dopant-free HTM for lead perovskite (MAPbI) solar cells. These organic/inorganic hybrid molecules are useful for tunable orbital level and controllable solubility. A fluorinated BDPSO has an energy level matched with MAPbI, affording an inverted-structure solar cell that performs with 17.2% efficiency with minimal hysteresis. The solar cell devices fabricated using BDPSOs showed remarkable storage and operational stability.
The fine structure in the solid state and phase transition behavior of newly synthesized comb copolymers having fluorocarbon and hydrocarbon side-chains were investigated by temperature controlled wide angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). From the WAXD profiles, two kinds of short spacing peaks based on the formation of the subcell for fluorinated and hydrogenated sidechains were confirmed at 5.0 and 4.1 Å , respectively. Furthermore, two kinds of endothermic peaks, which corresponded to melting peaks of both side-chain crystals, appeared in heating process of the DSC thermograms. From these experimental findings, the phase separation structure having the independently packed immiscible sidechain crystalline was formed in the whole polymer crystal. In addition, it was found that these comb polymers formed highly ordered (double) layer structure estimated using WAXD and small angle X-ray scattering (SAXS). These fluorinated comb copolymers form a monolayer on the water surface and their transferred film with phase-separated structure at nanometer size on solid. There were hydrogenated domains at 10-20 nm diameter scales in these phase separated surface structure of monolayers. From these experimental results, these copolymer monolayers are expected to be used as a new molecular device such as nanolithography based on the surface patterning of polymer nanomaterials. V V C 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: [416][417][418][419][420][421][422][423][424][425] 2006
The crystallization behavior of intercalated Poly(L‐lactide) (PLLA)/organo‐modified montmorillonite hybrids has been investigated in term of growth of spherulites and bulk crystallization. The PLLA hybrids were prepared via melt‐compounding between PLLA and montmorillonite organo‐modified (organoclay) with two different types of ammonium salts: trimethyl octadecyl‐ or bis(4‐hydroxy butyl) methyl octadecyl ammonium salts. The nucleation rate of PLLA crystallites is slightly enhanced by natural clay, while reduced by organoclay due to the shielding effect and/or miscibility between surfactants of clays and PLLA chains. The incorporation of small amount of organoclay in PLLA matrix shows a tendency to reduce slightly the growth rate and the overall crystallization rate of PLLA crystallites. The secondary nucleation theory was utilized to discuss the crystallization behavior of these hybrids. POLYM. ENG. SCI., 46:39–46, 2006. © 2005 Society of Plastics Engineers
We investigated the effects of surface-treated organophilic clay on the crystallization of poly(L-lactide) (PLLA) in their hybrids. The natural nano-clay in PLLA/ clay hybrids acts as a heterogeneous nucleating agent to facilitate crystallization. On the contrary, extensive distributions of induction periods for nucleation are observed in the individual spherulites of neat PLLA and PLLA/organophilic clay hybrids. Therefore, it is suggested that nucleation type of neat PLLA and PLLA/ organophilic clay hybrids implies nearly growth geometry as a homogeneous one. Further, under the presence of nano-clay in their composites, PLLA matrix form the orthorhombic lattice structure corresponded to the a-form crystal. Since this experimental fact implies little effect of the clay particles on polymorphism of PLLA crystal, the nucleating effect of the organophilic clay seems weaker than the natural clay itself. However, an increase in clay content enhances the growth rates of spherulite for hybrids. Consequently, most of hybrids exhibit an increase in overall crystallization rates at any crystallization temperature in spite of relatively lower nucleation rate of PLLA crystallites itself. In addition, the Avrami exponents (n) obtained by relatively low crystallization temperature ranged from 4 to 6, implying that the growth geometry was dominated sheaf-like structure in early stage of isothermal crystallization.
Films composed of poly(l‐lactide) (PLLA)/organophilic montmorillonite hybrids (PLACHs) have been prepared via a melt‐compounding process, which is followed by uniaxial drawing at 90°C in air. In addition, an enhancement of the mechanical properties of these drawn PLACH films, which is expected to differ depending on the drawn ratios, is also estimated by dynamic viscoelastic measurements. Three different organoclay concentrations in the hybrid of 3, 5, and 9 wt% were investigated. The structural parameters for the PLLA crystallites in the drawn films, such as the c‐axis orientation function (fPLLA) and crystallite size, were measured by X‐ray diffraction, and their drawn ratio (λ) and clay concentration dependence were examined from a textural viewpoint. Another orientation function (fclay) of the organoclay particles was obtained by transmission electron microscopy (TEM). The values of fPLLA and crystallinity for PLLA sharply increased with λ for λ < 3, although fclay was unchanged during the initial stage of elongation. In the high‐λ region (>5), the organoclay particles in the PLACHs started orienting themselves parallel to the draw direction. Copyright © 2008 John Wiley & Sons, Ltd.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.