Two hole‐extraction materials (HEMs), TPP‐OMeTAD and TPP‐SMeTAD, have been developed to facilitate the fabrication of efficient p‐i‐n perovskite solar cells (PVSCs). By replacing the oxygen atom on HEM with sulfur (from TPP‐OMeTAD to TPP‐SMeTAD), it effectively lowers the highest occupied molecular orbital of the molecule and provides stronger PbS interaction with perovskites, leading to efficient charge extraction and surface traps passivation. The TPP‐SMeTAD‐based PVSCs exhibit both improved photovoltaic performance and reduced hysteresis in p‐i‐n PVSCs over those based on TPP‐OMeTAD. This work not only provides new insights on creating perovskite‐HEM heterojunction but also helps in designing new HEM to enable efficient organic–inorganic hybrid PVSCs.
As a common feature in a majority of malignant tumors, hypoxia has become the Achilles’ heel of photodynamic therapy (PDT). The development of type‐I photosensitizers that show hypoxia‐tolerant PDT efficiency provides a straightforward way to address this issue. However, type‐I PDT materials have rarely been discovered. Herein, a π‐conjugated molecule with A–D–A configuration, COi6‐4Cl, is reported. The H2O‐dispersible nanoparticle of COi6‐4Cl can be activated by an 880 nm laser, and displays hypoxia‐tolerant type I/II combined PDT capability, and more notably, a high NIR‐II fluorescence with a quantum yield over 5%. Moreover, COi6‐4Cl shows a negligible photothermal conversion effect. The non‐radiative decay of COi6‐4Cl is suppressed in the dispersed and aggregated state due to the restricted molecular vibrations and distinct intermolecular steric hindrance induced by its four bulky side chains. These features make COi6‐4Cl a distinguished single‐NIR‐wavelength‐activated phototheranostic material, which performs well in NIR‐II fluorescence‐guided PDT treatment and shows an enhanced in vivo anti‐tumor efficiency over the clinically approved Chlorin e6, by the equal stresses on hypoxia‐tolerant anti‐tumor therapy and deep‐penetration imaging. Therefore, the great potential of COi6‐4Cl in precise PDT cancer therapy against hypoxia challenges is demonstrated.
The emulsifying properties of a natural cationic polysaccharide (chitosan) were improved by in situ conjugation with a natural essential oil (cinnamaldehyde, CA) during homogenization. In the absence of CA, chitosan-coated medium-chain triglyceride droplets were highly susceptible to creaming and coalescence at pH values ranging from 1 to 6.5. However, incorporation of relatively low levels of CA in the oil phase greatly improved the formation and stability of oil-in-water emulsions. These effects were attributed to two main factors: (i) covalent binding of lipophilic CA moieties to hydrophilic chitosan chains leading to conjugates with a good surface activity and (ii) interfacial cross-linking of adsorbed chitosan layers by CA leading to the formation of a rigid polymeric coating around the lipid droplets, which improved their stability against coalescence. The encapsulation technique developed in this study may be useful for applications in a range of commercial products; regulatory and flavor issues associated with chitosan and CA would have to be addressed.
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