Posts and reviews in P2P online lending platforms: a sentiment analysis and cross-culture comparison

P2P online lending platforms have been developing rapidly worldwide in recent years. This study seeks to explain platform users’ behaviour in different cultures. Specifically, this research aims to investigate the sentiment polarity of the posts in P2P online lending platforms and how it influences the quantity and quality of user reviews. Over 3000 online posts were collected from large online platforms in China and U.S. The findings indicate that in U.S. P2P online lending platforms, there are more reviews for negative-sentiment posts than those for positive-sentiment posts. In a collective culture such as China, there are more reviews in P2P online lending platforms for positive-sentiment posts, and platform participants tend to post strong sentiment information.</p

Tin(II) Acetylacetonate as a New Type of Tin Compensator Additive for Tin-Based Perovskite Solar Cells

Tin (Sn)-based perovskite is one of the most promising candidates for lead (Pb)-free perovskite light-absorbing materials applied in solar cells. However, the intrinsic Sn vacancy (VSn) defects seriously hinder the device performance, making the reported maximum power efficiency (PCE) of Sn-based perovskite solar cells (PSCs) far behind those of Pb-based ones. During the study, SnF2 has been demonstrated as an indispensable Sn compensator additive to improve the device performance. Considering that the default use of SnF2 and the selection of a Sn compensator has also been limited to tin­(II) halides, i.e., SnCl2, SnBr2, and SnI2, the role and work mechanism of the Sn compensator have not yet been clarified clearly. Herein, a new type of Sn compensator, tin­(II) acetylacetonate [Sn (acac)2], is introduced into Sn-based PSCs. It is found that in addition to tin compensation, the organic ligand acac– can coordinate with Sn2+ in the precursor solution and improve the crystallization process of perovskites. Consequently, the maximum PCE of formamidinium tin triiodide (FASnI3) solar cells is enhanced from 3.88 to 7.27% using Sn (acac)2 as the Sn compensator

Highly Efficient Heteroleptic Cerium(III) Complexes with a Substituted Pyrazole Ancillary Ligand and Their Application in Blue Organic Light-Emitting Diodes

Compared with red and green organic light-emitting diodes (OLEDs), blue is the bottleneck that restricts the wide development of OLEDs from being the next-generation technology for displays and lighting. As a new type of emitter, a Ce­(III) complex shows many satisfactory advantages, such as a short excited-state lifetime, 100% theoretical exciton utilization efficiency, and tunable emission color. Herein we synthesized three heteroleptic Ce­(III) complexes Ce­(TpMe2)2(dtfpz), Ce­(TpMe2)2(dmpz), and Ce­(TpMe2)2(dppz) with the hydrotris­(3,5-dimethylpyrazolyl)­borate (TpMe2) main ligand and different substituted pyrazole ancillary ligands, namely, 3,5-di­(trifluomethyl)­pyrazolyl (dtfpz), 3,5-dimethylpyrazolyl (dmpz), and 3,5-diphenylpyrazolyl (dppz), and studied their structures and luminescence properties. All the Ce­(III) complexes exhibited a near-unity photoluminescence quantum yield both in solution and as a powder with maximum emission wavelengths in the range of 450–486 nm. The OLED employing Ce­(TpMe2)2(dppz) as the emitter showed the best performance, including a turn-on voltage, maximum luminance, and external quantum efficiency of 3.2 V, 29 200 cd m–2, and 12.5%, respectively

Lanthanide Cerium(III) Tris(pyrazolyl)borate Complexes: Efficient Blue Emitters for Doublet Organic Light-Emitting Diodes

Organic light-emitting diodes (OLEDs) have had commercial success in displays and lighting. Compared to red and green OLEDs, blue OLEDs are still the bottleneck because the high-energy and long-lived triplet exciton in traditional blue OLEDs causes the short operational lifetime of the device. As a new type emitter, lanthanide complexes with a 5d–4f transition could have short excited-state lifetimes on the order of nanoseconds. To achieve a high-efficiency 5d–4f transition, we systematically tuned the steric and electronic effects of tripodal tris­(pyrazolyl)­borate ligands and drew a full picture of their Ce­(III) complexes. Intriguingly, all of these complexes show bright blue emission with high photoluminescence quantum yields exceeding 95% and short decay lifetimes of 35–73 ns both in the solid powder and in dichloromethane solutions. Using the Ce­(III) complex emitter, we show a blue OLED with a maximum external quantum efficiency of 14.1% and a maximum luminance of 33,160 cd m–2, and the specific electroluminescence mechanism of direct exciton formation on the Ce­(III) ion with a near-unity exciton utilization efficiency is also confirmed. The discovered photoluminescence and electroluminescence property–structure relationships may shed new light on the rational design of highly efficient lanthanide-based blue emitters and their optoelectronic devices such as OLEDs