The Non-fullerene Acceptors Based On Amide And Imide Derivatives With Spiro Structure

The non-fullerene acceptors can achieve flexible regulation of HOMO/LUMO level,broad absorption,better crystallization,and better miscibility with donor materials owing to the diversity of group modification,thereby it has been more and more popular in the field of organic solar cells.Remarkable,The PCE of organic solar cells based on non-fullerene acceptors have been exceeded 10%,which caught up the development of the traditional fullerene acceptors.When blended with donor material,some non-fullerene acceptors with great self-aggregation can form big domain size,which restrict the short-circuit current.Our previous research indicated that the molecules with spiro structure can interrupt self-aggregation of acceptors,which may be benefit to the high PCE.We synthesized some non-fullerene acceptors with spiro structure,amide and imide group in this paper,the basic photoelectric performance were tested,and they were used in the OPVs.Therefore,this paper consist of the following parts:1.We synthesized the molecules TPE-DPP and BFI-DPP by coupling TPE and BFI with DPP,and the structures were identified by HNMR.The UV-Vis spectra indicated the absorption was varying from 400nm to 800nm,TPE-DPP showed ACQ effect by fluorescence spectra.CV indicated the HOMO level of two molecule was-5.20eV and-5.32eV,the LUMO level of them was-3.68eV and-3.53eV.TGA curves revealed the temperature of 95%weight loss was 239?and 263?,which met the requirement of device fabrication.The PCE of the device based on P3HT as donor material and TPE-DPP as acceptor was 1.3%,which can be optimized to maintain higher PCE efficiency.2.TS-DPP₄ and TS-PDI₄ were synthesized by TS as building blocks andterminated with DPP and PDI,and the structures were identified by HNMR.The UV-Vis spectra of the acceptors was in visible light region,the molar extinction coefficient of them was 1.94×10⁵M^-1cm^-1 and 1.85×10⁵M^-1cm^-1,CV indicated the HOMO/LUMO level of TS-DPP₄ was-5.19eV/-3.50eV,and that of TS-PDI₄ was-5.62eV/-3.84eV.TGA showed they all have good thermal stability.The PCE of the device based on PTB7-Th as donor material and TS-PDI₄ as acceptor was 2.49%.3.SF-PyDPP and SF-3FDPP was synthesized by bonding SF with Py-DPP and3F-DPP,their structures were identified by HNMR.The UV-Vis spectra of them have great difference,ie.The edge of absorption for SF-PyDPP was about 640nm,the maximum absorption peak was about 550nm,which were about 70nm blue shift comparing with SF-3FDPP.Of course,The molar extinction coefficient was only 0.6times of that of SF-3FDPP.The CV curves indicated introducing trifluoriphenyl group to the structure have little influence on the energy levels,maybe a balance was achieved between the withdrawing effect of fluorine atom and the donating effect of phenyl group,which make a little difference of HOMO/LUMO levels between SF-3FDPP and SF-DPP.For contrast,We chose thiophene and indacenodithiophene as building blocks and Py-DPP as terminated group to synthesize T-PyDPP₂ and IDT-PyDPP₂,the structures were identified by HNMR.Comparison with other DPP derivatives,introducing Py-DPP to the structure resulted in blue shift of the maximum absorption peaks to about 550nm,and the molar extinction coefficient reduced obviously.The HOMO/LUMO levels of them was about-5.55eV/-3.50eV.relatively,HOMO level was low for the use as the acceptor for the donor materials with narrow band gap.TGA curves showed the 95%weight loss temperature of the acceptors were above 200?,they have good thermal stability.The PCE of the device based on SF-3FDPP as acceptor was about 1.67%,the other devices fabrication are still in progress.