A Wide Bandgap Acceptor with Large Dielectric Constant and High Electrostatic Potential Values for Efficient Organic Photovoltaic Cells

Low-bandgapmaterials have achieved rapid development and promotedthe enhancement of power conversion efficiencies (PCEs) of organicphotovoltaic (OPV) cells. However, the design of wide-bandgap non-fullereneacceptors (WBG-NFAs), required by indoor applications and tandem cells,has been lagging far behind the development of OPV technologies. Here,we designed and synthesized two NFAs named ITCC-Cl and TIDC-Cl byfinely optimizing ITCC. In contrast with ITCC and ITCC-Cl, TIDC-Clcan maintain a wider bandgap and a higher electrostatic potentialsimultaneously. When blending with the donor PB2, the highest dielectricconstant is also obtained in TIDC-Cl-based films, enabling efficientcharge generation. Therefore, the PB2:TIDC-Cl-based cell possesseda high PCE of 13.8% with an excellent fill factor (FF) of 78.2% underthe air mass 1.5G (AM 1.5G) condition. Furthermore, an exciting PCEof 27.1% can be accomplished in the PB2:TIDC-Cl system under the illuminationof 500 lux (2700 K light-emitting diode). Combined with the theoreticalsimulation, the tandem OPV cell based on TIDC-Cl was fabricated andexhibited an excellent PCE of 20.0%.

Automated summary

Low-bandgap materials have rapidly developed and improved the power conversion efficiencies of organic photovoltaic cells. However, the design of wide-bandgap non-fullerene acceptors (WBG-NFAs), necessary for indoor applications and tandem cells, has been lagging behind. In this study, two NFAs named ITCC-Cl and TIDC-Cl were successfully designed and synthesized. TIDC-Cl demonstrated a wider bandgap and higher electrostatic potential compared to ITCC and ITCC-Cl, resulting in efficient charge generation and a high PCE of 13.8% in PB2:TIDC-Cl-based cells.