2021 Adv. Mater. (IF 30.849), GS-ISO: WBG NFA realizes high performance and versatile photovoltaic applications

　　Advanced Materials (IF 30.849) published a research result in November 2021. The research team realized a high-performance nonfused wide-bandgap acceptor that can be used in versatile photovoltaic applications without using the fused ring structures.

　　In organic photovoltaic (OPV) cells, the wide-bandgap (WBG) non-fullerene acceptors (NFA) with a non-fusion conjugated structure plays a key role. In view of this, the research team synthesized NFAs named GS-OEH, GS-OC6 and GS-ISO without using fused ring structures. Their optical bandgaps were greater than 1.70 eV. Among these three types of NFA, GS-ISO exhibits stronger crystallinity than GS-OEH and GS-OC6, which resulted in smaller energy disorder and larger exciton diffusion coefficient. In addition, GS-ISO also exhibited a high electroluminescence external quantum efficiency of 1.0 × 10^-2.

　　Under the illumination of the solar simulator, with the standard silicon solar cell of Enlitech for light intensity correction, the OPV cell based on PBDB-TF:GS-ISO achieved 11.62% power conversion efficiency (PCE). In addition, under the illumination of 500 lux and 2700 K color temperature, the cell based on PBDB-TF:GS-ISO reached 28.37% PCE. Experiments were carried out through Enlitech’s QE-R quantum efficiency measurement system, FTPS Fourier transform photocurrent spectroscopy system, REPS photovoltaic Voc-loss analyzer and other instruments, and the results showed that by using PBDB-TF:GS-ISO as the front subcell, the tandem OPV cell exhibited an excellent PCE of 19.10%. Furthermore, OPV cell based on GS-ISO showed good stability under continuous irradiation of sun simulator. In addition to the EQE (External Quantum Efficiency) spectrum analysis of solar cells, the Quantum Efficiency Measurement System of Enlitech also provides Jsc (short-circuit current density) comparison for the short-circuit current of solar cells under the solar simulator to prove the authenticity of the experiment.

　　The results of this study shows that the molecular design strategy used in this study has great advantages in the development of nonfused NFA. GS-ISO is a WBG acceptor that can be used for multifunctional photovoltaic applications, which is quite promising.