Dithienobenzothiadiazole-Bridged Nonfullerene Electron Acceptors for Efficient Organic Solar Cells

Abstract

Advances of small-molecular acceptors (SMAs) recently have motivated the development of high-performance organic solar cells (OSCs). The SMAs featuring A–D–C–D–A framework have attracted numerous attention due to their facile tunability on chemical structures and in commercial synthesis. In this work, dithienobenzothiadiazol (DTBT) was utilized as the center (C) unit of A–D–C–D–A SMAs and three corresponding SMAs named DTBCIC-Cl, DTBCIC-F, and DTBCIC-H were synthesized by altering the terminal groups. The variation of terminal groups endowed SMAs with different performances, including optical absorbance, energy levels, and molecular packing, etc. In comparison to DTBCIC-H, DTBCIC-Cl and DTBCIC-F obtained by halogenation showed red-shift absorption, well matched energy levels with the polymer donor PM6, as well as closer molecular packing, rendering the blend films based on PM6:DTBCIC-Cl and PM6:DTBCIC-F wide absorption and improved morphology. High power conversion efficiency of 12.71% was thus obtained for OSCs based on DTBCIC-Cl. The results prove that optimization of SMAs via altering terminal groups provides a promising design strategy to obtain high-performance A–D–C–D–A SMAs.

Modification of the Electron‐Deficient Core on Unfused‐Ring Acceptors Enabling High Open‐Circuit Voltage of Organic Solar Cells

“…The results are tabulated in Table 2 , and the current density–voltage ( J – V ) characteristics and external quantum efficiencies (EQEs) curves are plotted in Figure . When blended with PM6, BTCD‐2FIC‐based blends performed nearly identical as previously reported, [ 40 ] giving the highest PCE of 11.4%, with a V OC of 0.894 V, a J SC of 19.79 mA cm −2 , and a FF of 64.5%. KS40‐based devices, despite slightly lower J SC , (18.82 mA cm −2 ), exhibited much higher V OC (0.945 V) and FF (68.7%), resulting in a higher PCE of 12.2%.…”

Phthalimide-based unfused-ring non-fullerene acceptors for constructing efficient organic solar cells with high open-circuit voltage

“…48 Theoretical calculations DFT calculations were conducted to examine the optimal geometries and frontier orbital energy levels of BPD-H, BPD-F, and BPD-Cl. 36 The results revealed that BPD-H, BPD-F, and BPD-Cl exhibited satisfactory backbone coplanarity because of the presence of intramolecular noncovalent interactions between the BPD and CPDT units and between the CPDT and terminal withdrawing units (Fig. 4a).…”

“…30,31 Duan et al , 32 Yu et al , 33 and Bo et al 34 developed UF-NFAs centered around a benzothiadiazole core, achieving an optimal PCE of 12.10%. Chen's group 35 and Huang's group 36 adopted novel UF-NFAs using dithienobenzothiadiazol as the building block modified terminal unit, yielding PCEs of 11.32% and 12.71%, respectively. Furthermore, using quinoxaline as the core and by fine-tuning terminal groups, Yang et al , 37 Chang et al 38 and He et al 39 achieved an optimal PCE of 12.32%.…”

Optimizing the Molecular Structure of Dithienophthalimide-Based Nonfused Ring Electron Acceptors for Efficient Organic Solar Cells

“…The regulation of the alkyl side chain and terminal halogenation modification are also effective strategies to finely adjust the photoelectric properties, molecular packing structure, and device performance of NFREAs. – In addition, the alkyl chain modification strategies can modulate solubility and molecular orientation to meet solution processing requirements and enhance charge separation and transport in NFREAs . For the terminal halogenation of NFREAs, we normally choose either fluorinated or chlorinated.…”