Effects of investor sentiment on stock volatility:new evidences from multi-source data in China’s green stock markets

The effect of investor sentiment on stock volatility is a highly attractive research question in both the academic field and the real financial industry.With the proposal of China’s"dual carbon"target,green stocks have gradually become an essential branch of Chinese stock markets.Focusing on 106 stocks from the new energy,environmental protection,and carbon–neutral sectors,we construct two investor sentiment proxies using Internet text and stock trading data,respectively.The Internet sentiment is based on posts from Eastmoney Guba,and the trading sentiment comes from a variety of trading indicators.In addition,we divide the realized volatility into continuous and jump parts,and then investigate the effects of investor sentiment on different types of volatilities.Our empirical findings show that both sentiment indices impose significant positive impacts on realized,continuous,and jump volatilities,where trading sentiment is the main factor.We further explore the mediating effect of information asymmetry,measured by the volume-synchronized probability of informed trading(VPIN),on the path of investor sentiment affecting stock volatility.It is evidenced that investor sentiments are positively correlated with the VPIN,and they can affect volatilities through the VPIN.We then divide the total sample around the coronavirus disease 2019(COVID-19)pandemic.The empirical results reveal that the market volatility after the COVID-19 pandemic is more susceptible to investor sentiments,especially to Internet sentiment.Our study is of great significance for maintaining the stability of green stock markets and reducing market volatility.

TTA as a potential hole transport layer for application in conventional polymer solar cells

Hole transport layers(HTLs)play a vital role in organic solar cells(OSCs).In this work,a derivative of tetrathiafulvalene with four carboxyl groups TTA was introduced as a novel HTL to fabricate OSC with high performance.Displaying a better energy level match between HTL and active layers,the TTA based devices show a peak power conversion efficiency of 9.09%,which is comparable to the devices based on PEDOT:PSS.The favorable surface morphology recorded via atomic force microscopy,low series loss and charge recombination indicated by electrochemical impedance spectroscopy,synchronously verify the potential of TTA for application in OSCs as a valid kind of HTLs.

三嗪石墨炔钝化晶界缺陷以提升钙钛矿太阳能电池的性能

钙钛矿晶界处的缺陷是造成非辐射复合和迟滞效应的主要原因.在本工作中,我们将三嗪石墨炔(一种富氮的碳材料)引入到钙钛矿中钝化晶界缺陷.实验结果表明,三嗪石墨炔能够均匀地分散于钙钛矿体相中,并且和晶界处暴露的Pb^2+发生强相互作用,这确保了三嗪石墨炔能够有效地钝化晶界,防止晶界离子迁移.开尔文电镜和荧光分析证明高度共轭的三嗪石墨炔存在于晶界处,有利于载流子的提取和传输.得益于晶界缺陷的钝化和高效的载流子传输,基于三嗪石墨炔的钙钛矿太阳能电池展现了更小的非辐射复合.因此,三嗪石墨炔优化后的MAPbI3器件光电转换效率为20.33%,迟滞效应可以忽略不计.同样地,将三嗪石墨炔的钝化方法拓展至FAPbI3器件中,得到了21.16%的最佳效率.本文展现的三嗪石墨炔钝化晶界缺陷的方法能够有效提升钙钛矿太阳能电池的性能和抑制迟滞效应.

Blast responses of shallow-buried prefabricated modular concrete tunnels reinforced by BFRP-steel bars

This paper reports the anti-blast performance of shallow-buried prefabricated modular tunnel reinforced by basalt fiber-reinforced polymer(BFRP)-steel bars.Three concrete arch members with steel bars and three concrete arch members with BFRP-steel bars were fabricated,with the other arch parameters kept constant.The three identical arches were assembled into an integral structure and then buried in soil for field anti-blast experiments.Through the experiment,the pressure on the vault,the displacement and acceleration of the vault,the strain in the reinforcement bars and the macroscopic damage of the arches under the blast load were determined.To evaluate the damage of the arch tunnel,a residual load-bearing capacity test was conducted on the arch members after the explosion experiment.The experimental results showed that the BFRP-steel bars reinforced concrete arch exhibited a higher load-bearing capacity and more safety redundancy than the steel bars reinforced concrete arch,and that the BFRP-steel bars could inhibit the occurrence of concrete cracks to a certain extent.A comparison between the arches assembled at different positions showed that the prefabricated modular tun-nel can be simplified directly as a two-dimensional arch structure under the blast load for analysis and calculation.

氧化石墨炔提升界面电荷传输及分离以构筑高效二元有机太阳能电池器件

通过界面工程调节载流子动力学是提高太阳能电池器件效率的关键方式.在本工作中,我们成功制备了具有大量官能团的高分散性氧化石墨炔(GDYO),并将其应用于优化空穴传输材料PEDOT:PSS的性质以制备有机太阳能电池器件.结果表明,GDYO与PEDOT:PSS之间的π–π相互作用有利于优化电荷转移通道,提高空穴传输层的电导率和载流子迁移率.此外,界面接触的改善有助于抑制电荷的复合,提高空穴传输层和活性层之间的电荷提取.同时,活性层的形貌得到有效改善,瞬态吸收测试结果证实这有利于载流子分离率的提升,进而提高器件性能.因此,通过对载流子动力学的系统性优化,二元有机太阳能电池的光电转换效率达到17.5%,认证效率达到17.2%.本工作结果表明功能化石墨炔在有机光电器件领域具有广阔的应用前景.