Unraveling Differences in the Effects of Ammonium/Amine-Based Additives on the Performance and Stability of Inverted Perovskite Solar Cells.

Additive engineering, with its excellent ability to passivate bulk or surface perovskite defects, has become a common strategy to improve the performance and stability of perovskite solar cells (PVSCs). Among the various additives reported so far, ammonium salts are considered an important branch. It is worth noting that although both ammonium-based additives (R-NH3 +) and amine-based additives (R-NH2) are derivatives of ammonia (NH3), the functions of the two can be easily confused due to their structural similarities. Moreover, there is no comprehensive comparative analysis of them in the literature. Here, the differences between phenethylammonium iodide (PEA+) and phenethylamine (PEA) additives are revealed experimentally and theoretically. The results clearly show that PEA outperforms PEA+ in terms of device performance and stability based on the following three factors: i) PEA's defect passivation capability is superior to that of PEA+; ii) PEA has better hydrophobicity to hinder water ingress; and iii) PEA completely improves the stability of PVSCs by enhancing thermal stability and inhibiting iodide migration in perovskite more effectively than PEA+. As a result, the power conversion efficiency (PCE) of the inverted methylammonium triiodide (MAPbI3) device using PEA increases by ≈15% to over 21%. More importantly, this device exhibits greater ability to prevent water invasion, thermal-induce degradation, and inhibit iodide ion migration, resulting in better long-term stability.

Identification of candidate flavonoid pathway genes using transcriptome correlation network analysis in ripe strawberry (Fragaria × ananassa) fruits.

New modulators of the strawberry flavonoid pathway were identified through correlation network analysis. The transcriptomes of red, ripe fruit from two parental lines and 14 of their progeny were compared, and uncharacterized transcripts matching the expression patterns of known flavonoid-pathway genes were identified. Fifteen transcripts corresponded with putative transcription factors, and several of these were examined experimentally using transient expression in developing fruits. The results suggest that two of the newly-identified regulators likely contribute to discrete nodes of the flavonoid pathway. One increases only LEUCOANTHOCYANIDIN REDUCTASE (LAR) and FLAVONOL 3'-HYDROXYLASE (F3'H) transcript accumulation upon overexpression. Another affects LAR and FLAVONOL SYNTHASE (FLS) after overexpression. The third putative transcription factor appears to be a universal regulator of flavonoid-pathway genes, as many pathway transcripts decrease in abundance when this gene is silenced. This report demonstrates that such systems-level approaches may be especially powerful when connected to an effective transient expression system, helping to provide rapid and strong evidence of gene function in key fruit-ripening processes.