Acta Phys. -Chim. Sin. ›› 2021, Vol. 37 ›› Issue (3): 2009056.doi: 10.3866/PKU.WHXB202009056

• REVIEW • Previous Articles     Next Articles

Semitransparent Organic Solar Cells based on Non-Fullerene Electron Acceptors

Baiqiao Liu1, Yunhua Xu1,*(), Dongdong Xia3, Chengyi Xiao2,*(), Zhaofan Yang2, Weiwei Li2,*()   

  1. 1 Department of Chemistry, School of Science, Beijing Jiaotong University, Beijing 100044, China
    2 State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, China
    3 Beijing National Laboratory for Molecular Sciences, Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2020-09-17 Accepted:2020-10-30 Published:2020-11-12
  • Contact: Yunhua Xu,Chengyi Xiao,Weiwei Li E-mail:yhxu@bjtu.edu.cn;xiaocy@mail.buct.edu.cn;liweiwei@iccas.ac.cn
  • About author:Weiwei Li. Email: liweiwei@iccas.ac.cn (W.L.)
    Chengyi Xiao. Email: xiaocy@mail.buct.edu.cn (C.X.)
    Yunhua Xu. Email: yhxu@bjtu.edu.cn (Y.X.)


  • Supported by:
    the National Natural Science Foundation of China(52073016);the National Natural Science Foundation of China(21905018);the Fundamental Research Funds for the Central Universities(XK1802-2)

Abstract:

Semitransparent organic solar cells (ST-OSCs) have attracted attention for use in building integrated photovoltaics because of their large range tunability in colors, transparency, and high efficiency. However, the development of semitransparent devices based on fullerene acceptors remained almost stagnant in the early period. This was due to the weak absorption of fullerene small molecules in the visible and near-infrared regions as well as the large non-radiative energy loss, resulting in drastic open-circuit voltage loss. In addition, the energy level and chemical structure of fullerene molecules cannot be easily regulated, and the strong aggregation characteristics of fullerenes greatly limit the development of OSCs. In contrast, the designability of the chemical structures and controllability of the energy levels of non-fullerene electron acceptors has encouraged researchers to explore high-performance organic solar cells while and simultaneously stimulating the development of ST-OSCs. In this review, the recent progress in non-fullerene small molecule acceptors for ST-OSCs is summarized. The article focuses on ST-OSCs from the aspects of device structures and active layers. In view of the semitransparent device structure, except for replacing the traditional electrodes with semitransparent electrodes, researchers have introduced suitable interface layers to regulate the absorption and reflection of sunlight. The interface layers mainly contain a reflective layer (evaporated on the top electrode to reflect near-infrared light); an anti-reflection layer (located below ITO (indium tin oxide)) to mitigate light reflection at the air-glass interface and thus enhance the absorption of sunlight); and an optical outcoupling layer (simultaneously increasing reflection and transmission). From the active layer, it is mainly divided into two categories. First, researchers have optimized the photovoltaic performance of semitransparent devices from the perspective of molecular structures, mainly by broadening the absorption window of non-fullerene small molecule acceptors, thus improving the crystallinity and charge mobility of small molecules, and regulating the stacking behavior and orientation of molecules in the films. Second, regarding the active layer processing, much effort has been undertaken to optimize the light absorption, morphology, and charge carrier transport channels of blended films.

Key words: Semitransparent organic solar cell, Non-fullerene acceptor, Average visible-light transmittance, Power conversion efficiency

MSC2000: 

  • O646