Enhancing photovoltaic performance by tuning the domain sizes of a small-molecule acceptor by side-chain-engineered polymer donors

Abstract

This paper reports side-chain-engineered polymer donors and a small-molecule acceptor that are capable of simultaneous charge and energy transfer as the active layer for organic photovoltaics.

Fluorinating π‐Extended Molecular Acceptors Yields Highly Connected Crystal Structures and Low Reorganization Energies for Efficient Solar Cells

“…[ 33 ] In addition, the major reflections observed in GIWAXS of the neat and blend films of both ITN‐F4 and ITzN‐F4 correlate with reflections observed in the simulated powder X‐ray diffraction patterns derived from the single crystal structures (Figures S7 and S8, Supporting Information), implying the presence of organized acceptor domains that resemble the single crystal structures. [ 25,34–38 ] In the following discussion, S⋯O distances will be abbreviated as D SO ( Figure 3 ) and end group‐core torsions will be abbreviated as φ (Figure 3). Crystallographic and electronic properties of ITN‐F4, ITzN‐F4, and their nonfluorinated counterparts (ITN‐C9 and ITzN‐C9), [ 25 ] non‐π‐extended counterpart (ITIC‐4F), and non‐π‐extended/nonfluorinated counterpart (ITIC) can be found in Table 2 .…”

“…The redundant packing [ 33 ] observed in the single crystal structure is expected to persist in the BHJ active layer, as grazing incidence wide‐angle X‐ray scattering (GIWAXS) d ‐spacings are consistent with those simulated using single crystal X‐ray data. [ 25,34–38 ] It will be seen that OSCs fabricated from ITzN‐F4 or ITN‐F4 and poly{[4,8‐bis[5‐(2‐ethylhexyl)‐4‐fluoro‐2‐thienyl]benzo[1,2‐ b :4,5‐ b ′]‐dithiophene‐2,6‐diyl]‐ alt ‐[2,5‐thiophenediyl[5,7‐bis(2‐ethylhexyl)‐4,8‐dioxo‐4 H ,8 H ‐benzo[1,2‐ c :4,5‐ c ′]dithiophene‐1,3‐diyl]]} (PBDB‐TF also known as PM6) exhibit promising power conversion efficiencies (PCEs) of 10.0% and 10.3%, respectively, without postdeposition processing. Interestingly, annealing ITzN‐F4:PBDB‐TF devices affords a similar PCE (10.3%), but lower open circuit voltages ( V OC s) and higher J SC s and fill factors (FFs).…”

Engineering the Core Units of Small‐Molecule Acceptors to Enhance the Performance of Organic Photovoltaics

“…In the low‐ q region, the GISAXS profiles of these blend films exhibited power‐law scattering at the exponent of –2 or slightly lower, indicative of a disk‐like morphology for the acceptor domains being the dominant contributor to the GISAXS intensity. [ 27 ] On the other hand, the middle‐ q region (0.01 Å −1 < q < 0.04 Å −1 ) of the GISAXS profile of the PTQ10:m‐ITIC‐OR‐4Cl blend film featured a power‐law scattering with an exponent of –1, mainly contributed by the rod‐like PTQ10 domain. The long‐rod morphology of the PTQ10 crystalline domains would be similar to the long‐fiber morphologies of the well‐established P3HT and BO2S crystallites formed by long‐chain packing [27b] .…”

2D Star‐Shaped Non‐Fullerene Electron Acceptors with Modulation of J‐/H‐Type Aggregations: Molecular Design–Morphology–Electrical Property Correlation

“…[ 10,13–15 ] However, the requirement of controlling the molecular packing orientation is a limitation of NFSMAs, as they tend to exhibit either face‐on or edge‐on orientations depending on the chemical structure and processing conditions. [ 16–18 ]…”