Donor-acceptor conjugated copolymer with high thermoelectric performance: A case study of the oxidation process within chemical doping

The doping process and thermoelectric properties of donor-acceptor(D-A)type copolymers are investigated with the representative poly([2,6-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene]3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophenediyl))(PTB7-Th).The PTB7-Th is doped by Fe Cl;and only polarons are induced in its doped films.The results reveal that the electron-rich donor units within PTB7-Th lose electrons preferentially at the initial stage of the oxidation and then the acceptor units begin to be oxidized at a high doping concentration.The energy levels of polarons and the Fermi level of the doped PTB7-Th remain almost unchange with different doping levels.However,the morphology of the PTB7-Th films could be deteriorated as the doping levels are improved,which is one of the main reasons for the decrease of electrical conductivity at the later stage of doping.The best electrical conductivity and power factor are obtained to be 42.3 S·cm^-1;and 33.9μW·mK^-1,respectively,in the doped PTB7-Th film at room temperature.The power factor is further improved to 38.3μW·mK^-1;at 75℃.This work may provide meaningful experience for development of D-A type thermoelectric copolymers and may further improve the doping efficiency.     

低成本富勒烯衍生物电子传输层在钙钛矿太阳能电池的应用（英文）

有机无机杂化钙钛矿太阳能电池(PSCs)近几年吸引了众多的关注。目前,在反式平板异质结钙钛矿太阳能电池中,最普遍使用的电子传输层材料是富勒烯衍生物PCBM,但是由于其价格昂贵,将会影响钙钛矿太阳能电池的最终产业化。本文开发出一种新的低成本富勒烯衍生物N-甲基-2-戊基[60]富勒烯吡咯烷(NMPFP)来取代PCBM,用于反式钙钛矿太阳能电池的电子传输层。和PCBM电子传输层相比,NMPFP具有更快的电子传输速率。用NMPFP制作的钙钛矿太阳能电池几乎没有迟滞现象,取得了13.83%的光电转换效率,和PCBM电池性能相当。而且,由于NMPFP更强的疏水性,其电池的稳定性优于PCBM电池。本研究表明NMPFP是一种非常有前景的电子传输材料,用于反式平板钙钛矿太阳能电池,可以有效的取代PCBM。     

Excited-State Dynamics of a Novel Bisimide-C60 Complex

The excited-state dynamics of a bisimide derivative (ZI) and a novel Z1-C60 complex (PSF) has been investigated by means of steady state optical spectroscopies and femtosecond time-resolved absorption spectroscopies. The lifetime of the singlet excited state of Z1 shortens drastically from 2.4 ns to 1.7ps upon going from Z1 to PSF, a significant kinetics change is in coincidence with the complete fluorescence quench caused by the C^60 attachment.Highly efficient Zl-to-C60 excitation energy transfer which is governed by the mechanism of Z1-C60 electron exchange has been verified for the PSF complex.