In-Depth Excavation and Screening of Triterpene Saponins From the Rhizome of Panax japonicus Using High Performance Liquid Chromatography Coupled to Electrospray Ionization and Quadrupole Time-of-Flight Mass Spectrometry.

The rhizome of Panax japonicus (RPJ) has been used for thousands of years in west China. Triterpene saponins (TSs) were considered to be the main pharmacologically bioactive ingredients in RPJ. However, it is difficult and time-consuming to profile and identify them according to the traditional phytochemical methods. High-performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS) was used for chemical identification of TSs from the extract of RPJ in negative ion mode. Their chemical structures were tentatively elucidated based on exact formulas, fragmentation patterns and literature data. In all, 42 TSs were discovered and tentatively characterized in RPJ, of which 12 TSs were identified as potential new compounds according to their molecular mass, fragmentation pattern and chromatographic behavior. The results demonstrated that the developed HPLC-ESI-QTOF-MS/MS method was conducive to the discovery of the active ingredients of RPJ and the establishment of quality standards.

Identification and characterization of the chemical constituents in the roots of Ilex asprella by high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry.

The roots of Ilex asprella (Rla) are a well-known traditional Chinese medicine for the treatment of viral and bacterial infectious diseases, such as influenza, tonsillitis, sphagitis, and trachitis. However, due to the complexity of the chemical constituents in Rla, few investigations have acquired a comprehensive understanding of material basis. High-performance liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS/MS) was used for the identification of chemical constituents from the extract of Rla in negative ion mode. Their chemical structures were tentatively elucidated based on exact formulas, fragmentation patterns and literature data. A total of 32 compounds were discovered and tentatively characterised in Rla, including 4 phenolic glycosides and 28 triterpenoid glycosides. 10 compounds have not been previously reported in Rla and 8 of them have not been previously reported in the literature. The chemical composition of Rla was identified and summarised, providing a basis for further study on Rla.

Potassium Salt Coordination Induced Ion Migration Inhibition and Defect Passivation for High-Efficiency Perovskite Solar Cells.

The disordered distribution of trap states and ion migration limit the commercial application of perovskite solar cells (PSCs). Herein, we apply an oxamic acid potassium salt (OAPS) as a bifunctional additive of perovskite film. The Lewis base group C=O of OAPS can interact with the uncoordinated Pb2+ caused by the I site substitution by Pb and the dangling bonds of the perovskite, which is beneficial to reduce the nonradiative recombination loss. In addition, the countercation K+ of OAPS is confirmed to occupy the perovskite lattice interstitial sites and result in lattice expansion, inhibiting the formation of iodide Frenkel defects and I- ion migration. As a result, the synergistic effect achieves enhanced power conversion efficiency (PCE) from 19.98 to 23.02%, with a fill factor reaching up to 81.90% and suppressed current-voltage hysteresis. The device also presents improved stability, maintaining 93% of the initial PCE after 2000 h of storage.

Enhanced Activation Energy Released by Coordination of Bifunctional Lewis Base d-Tryptophan for Highly Efficient and Stable Perovskite Solar Cells.

Perovskite defect passivation with molecule doping shows great potential in boosting the efficiency and stability of perovskite solar cells (PSCs). Herein, an efficient and low-cost bifunctional Lewis base additive d-tryptophan is introduced to control the crystallization and growth of perovskite grains and passivation defects. It is found that the additive doped in the solution precursors could retard crystal growth by increasing activation energy, resulting in improved crystallization of large grains with reduced grain boundaries, as well as inhibiting ion migration and PbI2 aggregation. As a result, the PSCs incorporated with d-tryptophan additives achieve an improved power conversion efficiency from 18.18 to 21.55%. Moreover, the d-tryptophan passivation agent improves the device stability, which retains 86.85% of its initial efficiency under ambient conditions at room temperature after 500 h. This work provides Lewis base small-molecule d-tryptophan for efficient defect passivation of the grain boundaries toward efficient and stable PSCs.

Strong Electron Acceptor of a Fluorine-Containing Group Leads to High Performance of Perovskite Solar Cells.

Organic-inorganic hybrid perovskites have become one of the most promising thin-film solar cell materials owing to their remarkable photovoltaic properties. However, nonradiative recombination of carriers usually leads to inferior performance of perovskite (PVK) devices. Interface modification is one of the effective ways to improve separation of charges for perovskite solar cells (PSCs). Here, a small organic molecule of tetrafluorophthalonitrile (TFPN) is used to enhance the extraction and transportation of carriers at the PVK/hole transport layer (HTL) interface. The electron-rich C-F group effectively reduces the trap state density in the perovskite through chemical combination with the empty orbital of Pb2+ or other electron traps on the PVK surface, resulting in enhanced interface contact between the PVK and HTL. Meanwhile, the C≡N group in TFPN also inactivates the defects caused by Pb2+. The Fermi level of the perovskite shifts by 0.15 eV to its valence band due to the strong electron acceptor nature of the F atom, indicating that positive dipoles and p-type doping emerge, which validly suppress the recombination of carriers for the PVK film. Therefore, the optimized PSC shows the highest power conversion efficiency (PCE) of 22.82% compared to 19.40% for the control one. The champion FF reaches up to 81.2% (PCE 21.44%) due to the effectively enhanced carrier separation. In addition, the unencapsulated device shows enhanced stability under air conditions.