A chlorinated copolymer donor demonstrates a 18.13% power conversion efficiency

Abstract

The rapid development of low-bandgap (LBG) nonfullerene acceptors and wide-bandgap (WBG) copolymer donors in recent years has boosted the power conversion efficiency (PCE) of organic solar cells (OSCs) to the 18% level [1−21] . The commercialization of OSCs is highly expected. However, critical issues like the cost and the stability also determine whether OSCs can enter the market or not [22] . Active materials, i.e. donors and acceptors, are the key materials determining the performance and cost of OSCs [23] . Nowadays, the state-of-the-art donors and acceptors like D18 [4] , PM6 [24] , Y6 [3] , IT-4F [25] and CO i 8DFIC [11] generally contain fluorine atoms, presenting high synthesis cost. Replacing fluorine with chlorine to make chlorinated donors or acceptors is an effective strategy to lower the cost while maintain the high efficiency for organic solar cells [26] . In the past few years, remarkable progress has been made in Cl-containing donors. In 2014, Wang et al. reported a chlorinated phenazine copolymer PCTClP with a low bandgap and a deep HOMO level [27] . Solar cells based on PCTClP and a fullerene acceptor PC 71 BM gave a PCE of 4.06%. In 2015, Pei et al. designed a chlorinated isoindigo copolymer Cl-IIDT [28] . Thanks to the chlorination, Cl-IIDT shows reduced crystallinity and a preferred faceon orientation, delivering a PCE of 4.60% in fullerene-based solar cells. In 2017, He et al. used monochlorinated benzothiadiazole unit as the building block to construct an asymmetric copolymer donor PBDTHD-ClBTDD [29] . The PBDTHD-ClBT-DD:PC 71 BM cells afforded decent PCEs up to 9.11%. In the same year, Peng et al. developed an efficient small molecular

Recent Advances of Chlorination in Organic Solar Cells

“…exhibited a better performance than that of PBBD-Cl-. Recently, our group 19 and the Ding group 20 separately reported a new polymer donor, D18-Cl, with the BDT-Cl as the donor unit. When combined with N3 as the acceptor, both groups achieved excellent performance of OSCs with a recorded PCE of 18.13%.…”

Exploring the Charge Dynamics and Energy Loss in Ternary Organic Solar Cells with a Fill Factor Exceeding 80%

“…Ternary OSCs commonly show extended coverage of the solar irradiance spectrum, boosting short-circuit current density (J sc ) and power conversion efficiency (PCE). [1][2][3][4][5] However, with the development of the state-of-the-art donors and non-fullerene acceptors (NFAs) featuring strong and broad light absorption; [6][7][8][9][10][11][12][13][14][15][16][17] in fact, there is not much room to improve PCEs by adopting ternary architectures in terms of enhancing light absorption, and the contribution in the enhanced J sc originates instead from fine-tuning of film morphology in ternary devices. [18,19] According to the equation: PCE = J sc × V oc × FF/P light (V oc is open-circuit voltage, FF is fill factor, and P light is light intensity), the FF is an important parameter determining the final PCE.…”

18.77 % Efficiency Organic Solar Cells Promoted by Aqueous Solution Processed Cobalt(II) Acetate Hole Transporting Layer

“…Organic solar cells (OSCs) have emerged as ap romising energy technology alternative to the traditional inorganic solar cells owing to their appealing potentials in solution processing of cost-effective large-area and flexible devices. [1] Therecent advances in nonfullerene acceptors matched with appropriate polymer donors and used as the photoactive layer have boosted the power conversion efficiency (PCE) of OSCs over 18 %, [2] which is on par with commercial silicon based solar cells,p ointing to ab right future for the practical applications of OSCs. [3] In addition to the advances in photoactive materials, interfacial layers also play an equally important role in improving not only the device performance but also the device stability of OSCs.…”