Fused Cyclopentadithienothiophene Acceptor Enables Ultrahigh Short‐Circuit Current and High Efficiency >11% in As‐Cast Organic Solar Cells

Abstract

A new method to synthesize an electron-rich building block cyclopentadithienothiophene (9H-thieno-[3,2-b]thieno[2″,3″:4′,5′]thieno[2′,3′:3,4] cyclopenta[1,2-d]thiophene, CDTT) via a facile aromatic extension strategy is reported. By combining CDTT with 1,1-dicyanomethylene-3-indanone endgroups, a promising nonfullerene small molecule acceptor (CDTTIC)is prepared. As-cast, single-junction nonfullerene organic solar cells based on PFBDB-T: CDTTIC blends exhibit very high short-circuit currents up to 26.2 mA cm −2 in combination with power conversion efficiencies over 11% without any additional processing treatments. The high photocurrent results from the near-infrared absorption of the CDTTIC acceptor and the well-intermixed blend morphology of polymer donor PFBDB-T and CDTTIC. This work demonstrates a useful fused ring extension strategy and promising solar cell results, indicating the great potential of the CDTT derivatives as electron-rich building blocks for constructing high-performance small molecule acceptors in organic solar cells.

Over 14% efficiency all-polymer solar cells enabled by a low bandgap polymer acceptor with low energy loss and efficient charge separation

“…34 Matching with wide bandgap polymer donors such as PBDB-T or PM6, the resulting all-PSCs showed a high J sc of 16.05-17.1 mA cm À2 and impressive PCEs in the range of 9.19-11.2%. 23,34 However, compared to high-performance SM-acceptors with broader absorption spectra and a higher absorption coefficient and thus a high J sc of the resulting PSCs, 1,3,[39][40][41][42] PZ1 still exhibits limited J sc when implemented in all-PSCs. For example, the SM-acceptor Y5 shows an absorption onset wavelength of B890 nm with a high absorption coefficient of B1.24 Â 10 5 cm À1 due to its unique benzothiadiazole (BT)-fused A 1 -DA 2 D-A 1 -type building block.…”

Exceptionally low charge trapping enables highly efficient organic bulk heterojunction solar cells

“…15 These high performance characteristics have been attributed in part to its long wavelength absorption onset (B900 nm) and complementary donor and acceptor absorption, large absorption extinction coefficients, and moderate HOMO and LUMO energy offsets. 5,[16][17][18][19] More in depth studies by Karki et al and Perfigon-Toro et al have identified several additional factors which may be critical to this blend's high performance, including efficient charge generation with barrierless CT state dissociation, and a nanomorphology favourable for charge separation. 15,20,21 The achievement of both high EQEs over 80% (up to 900 nm) and a low voltage loss in this blend has been highlighted as particularly remarkable.…”

Constructing High‐Performance Organic Photovoltaics via Emerging Non‐Fullerene Acceptors and Tandem‐Junction Structure

“…With those in mind, tremendous progresses have been made by many groups. Some representative IR‐absorbing non‐fullerene acceptors with narrow bandgaps that have been synthesized include: Y1 (1.44 eV), [ 21 ] CDTTIC (1.44 eV), [ 22 ] DOC2C6‐2F (1.42 eV), [ 23 ] AOIC (1.39 eV), [ 24 ] FNIC2 (1.38 eV), [ 25 ] AQx‐2 (1.35 eV), [ 26 ] Y6 (1.33 eV), [ 27 ] FOIC (1.32 eV), [ 28 ] BT‐CIC (1.3 eV), [ 29 ] F8IC (1.27 eV), [ 30 ] COi8DFIC (1.26 eV), [ 31 ] IEICO‐4F (1.24 eV), [ 32 ] DTPC‐DFIC (1.21 eV). [ 33 ] Combined with large/medium bandgap donors, single‐junction devices based on these acceptors can achieve very high J SC (26–28 mA cm −2 ).…”