Miscibility‐Controlled Phase Separation in Double‐Cable Conjugated Polymers for Single‐Component Organic Solar Cells with Efficiencies over 8 %

Abstract

Arecordpower conversion efficiency of 8.40 %was obtained in single-component organic solar cells (SCOSCs) based on double-cable conjugated polymers.T his is realized based on exciton separation playing the same role as charge transport in SCOSCs.T wo double-cable conjugated polymers were designed with almost identical conjugated backbones and electron-withdrawing side units,b ut extra Cl atoms had different positions on the conjugated backbones.W hen Cl atoms were positioned at the main chains,the polymer formed the twist backbones,e nabling better miscibility with the naphthalene diimide side units.T his improves the interface contact between conjugated backbones and side units,resulting in efficient conversion of excitons into free charges.T hese findings reveal the importance of charge generation process in SCOSCs and suggest as trategy to improve this process: controlling miscibility between conjugated backbones and aromatic side units in double-cable conjugated polymers.

Molecular Donor–Acceptor Dyads for Efficient Single‐Material Organic Solar Cells

“…In comparison, the best-performing "double-cable" polymers showed a significantly enhanced hole and electron mobility upon thermal annealing; however, no balance of the carriers was achieved and hole mobility always was higher by two to three orders of magnitude. [11,12] 2.7. Film Morphology…”

“…In this respect, Li and coworkers very recently improved the PCE of SMOSCs to an impressive 8.4% by developing a new “double‐cable” polymer constructed of a benzodithiophene‐based donor backbone with appended naphthalene diimides. [ 11 ] Interestingly, a thermally driven phase separation into lamellar structures was achieved at higher temperatures for a similar type of polymer, leading to an unexpectedly high thermal and light stability [ 12 ] so far inconceivable for solution‐processed binary or ternary BHJ‐OSCs.…”

Narrow‐Bandgap Single‐Component Polymer Solar Cells with Approaching 9% Efficiency

“…Single‐component organic solar cells (SCOSCs) are under investigation due to their advantage in minimizing procedures for preparing ready‐to‐coat organic conductive ink and photoactive layer, as well as their remarkably stable morphology. [ 1–5 ] In general, SCOSCs can be classified into three main categories according to the molecular structure of the photovoltaic materials, which are block conjugated polymers, [ 6–8 ] organic–fullerene molecular dyads, [ 4,9–12 ] and recently emerged “double‐cable” conjugated polymers. [ 1–3,13 ] It is worth noting that SCOSCs have already exhibited superiority in simplifying device fabrication, improving device stability, and more.…”

“…[ 1–5 ] In general, SCOSCs can be classified into three main categories according to the molecular structure of the photovoltaic materials, which are block conjugated polymers, [ 6–8 ] organic–fullerene molecular dyads, [ 4,9–12 ] and recently emerged “double‐cable” conjugated polymers. [ 1–3,13 ] It is worth noting that SCOSCs have already exhibited superiority in simplifying device fabrication, improving device stability, and more. [ 4,14 ] However, the performance of the state‐of‐the‐art SCOSC still lags significantly behind that of binary and ternary organic solar cells, which is mainly attributed to the relatively low short‐circuit current density ( J sc ).…”

“…[ 19–21 ] For instance, Li et al reported a series of “double‐cable” conjugated polymers consisting of linear donor–acceptor conjugated backbones and electron deficient NDI side‐chains. Through precisely controlling the molecular structure, miscibility and morphology, a record PCE over 8% was first reported for SCOSCs, [ 1 ] which is notably improved compared to the devices based on widely studied block polymers and molecular dyads. However, in the form of the current grafted “double‐cable” conjugated polymers, [ 1–3 ] it only allows for a relatively wide bandgap ≈1.8 eV.…”