A non-fullerene acceptor based on alkylphenyl substituted benzodithiophene for high efficiency polymer solar cells with a small voltage loss and excellent stability

Abstract

A new small molecule acceptor named BP-4F is developed. The optimal PSC based PM6:BP-4F achieves an excellent average PCE of 13.9% with an Eloss of 0.59 eV and outstanding stability.

Ladder‐Type Heteroheptacenes with Different Heterocycles for Nonfullerene Acceptors

“…Furthermore,the geometry of M34 is beneficial for an improved p-pstacking compared to its sp 3 carbon atom-containing analogue with the removal of out-of-plane side-chains. [32] Forb oth acceptors,t heir LUMOs delocalize over nearly the entire pconjugated systems (non-aromatic quinoidal form) with no contribution from the alkyl side chains as well as the heteroatoms in the furan (or thiophene in the same position). Fort his reason, the LUMO energy levels are only slightly affected by the replacement of oxygen atoms with sulfur atoms (À3.65 eV for M8, and À3.66 eV for M34) which is generally in agreement with the experimental results.H owever,t he HOMOs of both acceptors reside primarily on the ladder-type heteroheptacenes including the furan (or thiophene in the same position) rings as well as the malononitrile groups.D ue to the increased aromaticity index of the thiophene-based heteroheptacene in comparison with that of the furan-based heteroheptacene,t he HOMO of M34 becomes lower in energy with the greater aromatic stabilization energy.T herefore, M34 showed ad eeper HOMO energy level of À5.70 eV in relative to that of À5.64 eV for M8.…”

“…It should be noted that the planar geometry is beneficial for efficient carrier transport. Furthermore, the geometry of M34 is beneficial for an improved π–π‐stacking compared to its sp 3 carbon atom‐containing analogue with the removal of out‐of‐plane side‐chains [32] . For both acceptors, their LUMOs delocalize over nearly the entire π‐conjugated systems (non‐aromatic quinoidal form) with no contribution from the alkyl side chains as well as the heteroatoms in the furan (or thiophene in the same position).…”

2D Side‐Chain Engineered Asymmetric Acceptors Enabling Over 14% Efficiency and 75% Fill Factor Stable Organic Solar Cells

“…Importantly, the 2D conjugated IPT2F-TT based devices outperform N-octylated IPT-2F based ones (PCE 13.70%, FF 71.50%) when blended with the same polymer donor PBDB-T. [33] To the best of our knowledge, the PCE of 14.02% and FF over 75% are among the highest values for best-performing 2D conjugated FREAs based binary OSCs in the literature (Figure 2a, Table S1, Supporting Information), e.g. PBDB-T:BTTIC-TT (PCE 13.44%, FF 74.20%), [33] PBDB-T:BTTIC-Th (PCE 12.91%, FF 73.60%), [33] PM6:FBDT-4Cl (PCE 12.36%, FF 70.19%), [15] PTB7-Th:FNIC2 (PCE 13.00%, FF 73.40%), [11] PM6:BP-4F (PCE 13.90%, FF 72.00%), [21] FTAZ:ITIC2 (PCE 11.00%, FF 63.00%). [22] As a comparison, PBDB-T:IPT2F-Th and PBDB-T:IPT2F-Ph based devices delivered moderate PCEs of 12.52% and 13.13%, respectively.…”

Ladder‐Type Heteroheptacenes with Different Heterocycles for Nonfullerene Acceptors

“…Furthermore,the geometry of M34 is beneficial for an improved p-pstacking compared to its sp 3 carbon atom-containing analogue with the removal of out-of-plane side-chains. [32] Forb oth acceptors,t heir LUMOs delocalize over nearly the entire pconjugated systems (non-aromatic quinoidal form) with no contribution from the alkyl side chains as well as the heteroatoms in the furan (or thiophene in the same position). Fort his reason, the LUMO energy levels are only slightly affected by the replacement of oxygen atoms with sulfur atoms (À3.65 eV for M8, and À3.66 eV for M34) which is generally in agreement with the experimental results.H owever,t he HOMOs of both acceptors reside primarily on the ladder-type heteroheptacenes including the furan (or thiophene in the same position) rings as well as the malononitrile groups.D ue to the increased aromaticity index of the…”