Fullerene-Based Triads with Controlled Alkyl Spacer Length as Photoactive Materials for Single-Component Organic Solar Cells

Abstract

Two kinds of dumbbell-shaped acceptor–donor–acceptor (A–D–A)-type triad single-component (SC) photovoltaic molecules based on a benzodithiophene-rhodanine (BDTRh) core and [6,6]-phenyl-C61 butyric acid (PC61BA) termini, BDTRh–C2–PC61BA and BDTRh–C10–PC61BA, were synthesized by modulating the alkyl (C2 and C10) spacer lengths. Both SC photovoltaic structures had similar UV–vis spectra in solution, but BDTRh–C10–PC61BA showed a significantly higher absorption coefficient as a thin film. In films, a more facile intermolecular photo-induced charge transfer was observed for BDTRh–C10–PC61BA in the broad-band transient absorption measurements. BDTRh–C10–PC61BA also exhibited a higher hole mobility (by 25 times) and less bimolecular recombination than BDTRh–C2–PC61BA. By plotting the normalized external quantum efficiency data, a higher charge-transfer state was measured for BDTRh–C10–PC61BA, reducing its voltage loss. A higher power conversion efficiency of ∼2% was obtained for BDTRh–C10–PC61BA, showing higher open-circuit voltage, short-circuit current density, and fill factor than those of BDTRh–C2–PC61BA devices. The different carrier dynamics, voltage loss, and optical and photoelectrical characteristics depending on the spacer length were interpreted in terms of the film morphology. The longer decyl spacer in BDTRh–C10–PC61BA afforded a significantly enhanced intermolecular ordering of the p-type core compared to BDTRh–C2–PC61BA, suggesting that the alkyl spacer length plays a critical role in controlling the intermolecular packing interaction.

Achieving More Insight on the Dynamic Process from Conventional/Inverted Layer‐by‐Layer All‐Polymer Solar Cells with 17.24% or 12.41% Efficiency

“…As seen from the Figure 3a, there is small Stock shift between PL emission peak and absorption peak of PM6, leading to the longer exciton diffusion distance through the self‐absorption effect. [ 15,28 ] The longer exciton diffusion distance should be conducive to increasing exciton dissociation efficiency, especially in the LbL‐PSCs. There is large spectral overlapping between PL spectrum of PM6 and absorption spectrum of PY‐DT, indicating the potential energy transfer from PM6 to PY‐DT.…”

Synthesis of an Adaptable Molecular Barrel and Guest Mediated Stabilization of Its Metastable Higher Homologue

“…Fullerenes, due to their interesting physicochemical properties, find applications in several fields. − The major drawback of working with fullerenes is their poor solubility in common organic solvents. Functionalization of fullerenes to generate soluble derivatives has been the common technique employed to overcome this issue.…”

Polymer solar cells made with photocrosslinkable conjugated donor–acceptor block copolymers: improvement in the thermal stability and morphology with a single-component active layer

“…Single-component polymers such as doublecable polymers and conjugated donor-acceptor block copolymers (CDABPs) have been proposed for use in many strategies. [14][15][16][17][18][19][20][21] CDABPs reduce the large phase separation of donor and acceptor domains through the improvement of internal morphology, facilitate the fabrication of single-component polymer solar cells (SCPSCs). [22][23][24] In several studies, CDABPs were synthesized through onepot polymerization, in which a crystallizable donor and acceptor macromolecular units are introduced into the same polymer chain to solve the miscibility problem and tune charge transport properties.…”

“…Single-component polymers such as double-cable polymers and conjugated donor–acceptor block copolymers (CDABPs) have been proposed for use in many strategies. 14–21 CDABPs reduce the large phase separation of donor and acceptor domains through the improvement of internal morphology, facilitate the fabrication of single-component polymer solar cells (SCPSCs). 22–24…”