Modification of NFA-Conjugated Bridges with Symmetric Structures for High-Efficiency Non-Fullerene PSCs.

Qiuchen Lu,Yuanzuo Li,Zhuo Li,Meiyu Zhao,Ming Qiu

doi:10.3390/polym11060958

Qiuchen Lu, Yuanzuo Li + Show 3 more

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https://doi.org/10.3390/polym11060958

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Abstract

As electron acceptors, non-fullerene molecules can overcome the shortcomings of fullerenes and their derivatives (such as high cost, poor co-solubility, and weak light absorption). The photoelectric properties of two potential non-fullerene polymer solar cells (PSCs) PBDB-T:IF-TN (PB:IF) and PBDB-T:IDT-TN (PB:IDT) are studied by density functional theory (DFT) and time-dependent DFT (TD-DFT). Based on the optimized structure of the ground state, the effects of the electron donor (D) and electron acceptor (A) (D/A) interfaces PBDB-T/IF-TN (PB/IF) and PBDB-T/IDT-TN (PB/IDT) are studied by a quantum-chemical method (QM) and Marcus theory. Firstly, for two non-fullerene acceptors (NFAs) IF-TN and IDT-TN, the NFA IDT-TN has better optical absorption ability and better electron transport ability than IF-TN. Secondly, for the D/A interfaces PB/IF and PB/IDT, they both have high optical absorption and electron transfer abilities, and PB/IDT has better optical absorption and lower exciton binding energy. Finally, some important parameters (open-circuit voltage, voltage loss, fill factor, and power conversion efficiency) are calculated and simulated by establishing the theoretical model. From the above analysis, the results show that the non-fullerene PSC PB:IDT has better photoelectric characteristics than PB:IF.

Highlights

With the depletion of traditional fossil energy and serious environmental pollution, it is urgent to find new, clean, and sustainable energy
The energy conversion process of polymer solar cells (PSCs) is divided into four basic steps [11,12]: (1) Sunlight excites the active layer molecules, and excitons are formed in the active layer; (2) the excitons are diffused to the interfaces of the electron donor (D) and the electron acceptor (A) (D/A interfaces); (3) the excitons undergo charge separation at the D/A interfaces, generating electrons and hole carriers; (4) charges are transferred to the electrodes to generate current
The charge difference density (CDD) plots of the small investigated by using the density functional theory (DFT)/PW91PW91/6-31G(d) method involved in Marcus theory [44]

Summary

Introduction

With the depletion of traditional fossil energy and serious environmental pollution, it is urgent to find new, clean, and sustainable energy. Solar energy is an excellent clean, sustainable, and new energy, and solar cells are important devices for the efficient collection and utilization of solar energy [1,2,3,4,5,6]. The energy conversion process of PSCs is divided into four basic steps [11,12]: (1) Sunlight excites the active layer molecules, and excitons are formed in the active layer; (2) the excitons are diffused to the interfaces of the electron donor (D) and the electron acceptor (A) (D/A interfaces); (3) the excitons undergo charge separation at the D/A interfaces, generating electrons and hole carriers; (4) charges are transferred to the electrodes to generate current. The active layer, as an important part of the PSCs, is generally composed of electron donors and electron acceptors [13], which are Polymers 2019, 11, 958; doi:10.3390/polym11060958 www.mdpi.com/journal/polymers

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