Interface engineering is one feasible and effective approach to minimize the interfacial nonradiative recombination stemming from interfacial defects, interfacial residual stress, and interfacial energy level mismatch. Herein, a novel and effective steric-hindrance-dependent buried interface defect passivation and stress release strategy is reported, which is implemented by adopting a series of adamantane derivative molecules functionalized with CO (i.e., 2-adamantanone (AD), 1-adamantane carboxylic acid (ADCA), and 1-adamantaneacetic acid (ADAA)) to modify SnO 2 /perovskite interface. All modifiers play a role in passivating interfacial defects, mitigating interfacial strain, and enhancing device performance. The steric hindrance of chemical interaction between CO in these molecules and perovskites as well as SnO 2 is determined by the distance between CO and bulky adamantane ring, which gradually decreases from AD, ADCA, and ADAA. The experimental and theoretical evidences together confirmed steric-hindrance-dependent defect passivation effect and interfacial chemical interaction strength. The interfacial chemical interaction strength, defect passivation effect, stress release effect and thus device performance are negatively correlated with steric hindrance. Consequently, the ADAA-modified device achieves a seductive efficiency up to 23.18%. The unencapsulated devices with ADAA maintain 81% of its initial efficiency after aging at 60 °C for 1000 h.
A new benzoxazole-modified [PhSiO 1.5 ] 8 (OPS) benzoxazine (OPS−Bz) was synthesized and used to prepare polyhedral oligomeric silsesquioxane (POSS)/ polybenzoxazine (PBz) nanocomposites. Fourier transform infrared spectroscopy (FTIR), 1 H NMR, 29 Si NMR, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the structure of OPS−Bz. The high resolution transmission electron microscopy images of POSS/PBz(30/70) nanocomposites showed a well separated nanostructure of POSS with a typical phase size of 3−10 nm. POSS was highly dispersed in the polymer matrix because of the benzoxazole groups around the OPS molecular, in which the rigid benzoxazole groups increased the distance among the POSS molecules and reduced the aggregation of POSS nanoparticles. The TGA study showed these nanocomposites possess good thermal stability. Moreover, the dielectric constants and dielectric loss of these POSS/PBz nanocomposites were low and changed slightly at room temperature in the frequency range of 10 Hz to 1 MHz.
Perovskite solar cells suffer from poor reproducibility due to the degradation of perovskite precursor solution. Herein, we report an effective precursor stabilization strategy via incorporating 3-hydrazinobenzoic acid (3-HBA) containing carboxyl (À COOH) and hydrazine (À NHNH 2 ) functional groups as stabilizer. The oxidation of I À , deprotonation of organic cations and amine-cation reaction are the main causes of the degradation of mixed organic cation perovskite precursor solution. The À NHNH 2 can reduce I 2 defects back to I À and thus suppress the oxidation of I À , while the H + generated by À COOH can inhibit the deprotonation of organic cations and subsequent amine-cation reaction. The above degradation reactions are simultaneously inhibited by the synergy of functional groups. The inverted device achieves an efficiency of 23.5 % (certified efficiency of 23.3 %) with an excellent operational stability, retaining 94 % of the initial efficiency after maximum power point tracking for 601 hours.
Introduction of large pore in the primitive microporous metal–organic frameworks (MOFs) with tailorable particle size can endow them with desired properties for potential applications in the intracellular delivery of membrane‐impermeable proteins. However, no research is found to focus on this topic until now. Herein, a monocarboxylic acid (MA) and organic base comodulation strategy is developed to synthesize the hierarchically porous UiO‐66 nanoparticles. MA of dodecanoic acid is utilized to control the pore size while trimethylamine (TEA) plays a key role in modulating the nucleation of crystallization to regulate the particle size. In comparison with microporous UiO‐66, a model protein of cytochrome c (Cyt c) could be efficiently loaded into the mesoporous MOFs (mesoMOFs). The size‐dependent cellular uptake is also evaluated, and it is verified that mesoMOFs with particle size of 90 nm could be endocytosed into living cells with highest efficiency. These outstanding merits enable the current mesoMOFs not only to exhibit efficient encapsulation of Cyt c but also facilitate the protein delivery into the cytosol and subsequent endosomal escape. Given the exceptional chemical stability, hierarchically porous structure as well as tunable particle size, the elaborated mesoUiO‐66 nanoparticles might offer a promising platform for a variety of biomedical applications.
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