Crystalline Cooperativity of Donor and Acceptor Segments in Double‐Cable Conjugated Polymers toward Efficient Single‐Component Organic Solar Cells

Abstract

The crystalline cooperativity of the donor and acceptor segment in double‐cable conjugated polymers plays an important role in the nanophase separation and photovoltaic performance in single‐component organic solar cells (SCOSCs). Two double‐cable conjugated polymers with the same conjugated backbone and perylene bisimide (PBI) side units were designed in which PBIs were positioned symmetrically and perpendicularly (P1) and asymmetrically and slantingly (P2) along the conjugated backbones. After thermal annealing, both conjugated backbones and PBI side units in P1 tend to form ordered nanostructures, while PBI side units in P2 dominated the crystallization and hamper the crystallization of conjugated backbones. P1 showed good crystalline cooperativity between conjugated backbones and PBI side units, resulting in improved power conversion efficiencies (PCEs) up to 3.43 % in SCOSCs, while P2 with poor crystalline cooperativity exhibited PCEs below 2.42 %.

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

“…From atomic force microscopy measurement, it clearly showed that the optimized JP01 and JP02 thin films had relatively low roughness with small domain size (Supporting Information, Figure S8 b and Figure S9 b), indicating that better nanophase separation between backbones and NDIs could be obtained. Similar phenomenon could also be observed in our previous study, in which good crystalline cooperativity was linked to good nanophase separation [7k] . Further studies by GIWAXS revealed that these optimized thin films had relatively high CLs of q 2 / q 001 and q 010 peaks, corresponding to the better molecular packings (Supporting Information, Figure S10 and Table S9).…”

“…We have been particularly interested in double‐cable conjugated polymers for application in SCOSCs since they could be synthesized via a controllable manner, in which a series of functionalized monomers with pendent electron acceptors were prepared for palladium‐catalyzed polymerization [11] . This enabled us to incorporate the widely reported conjugated polymers and electron acceptors into double‐cable polymers, providing tunable optical and electrical properties [7h–m, 12] . Among them, we found that the linear conjugated backbones [7h] and post‐thermal treatment [7i] could facilitate the simultaneous self‐assembly of conjugated backbones and aromatic side units, generated well‐ordered nanophase separation, and hence provided external quantum efficiencies (EQEs) above 0.65 and PCEs over 6 %.…”

Control of aggregated structure of photovoltaic polymers for high‐efficiency solar cells

“…The control of aggregated structure of the polymer acceptors, [405][406][407][408][409][410] double-cable polymers [411][412][413][414] and multicomponent polymer blends remains a critical hurdle. These complex material systems may exhibit different aggregation behaviors, remaining challenges for controlling the aggregated structure of corresponding systems.…”

Flexible Organic Solar Cells: Progress and Challenges

“…In the past 5 years, PCEs of 12–16% have been achieved in various NFAs cases via rational designing of the A and D unit chemical structures. [ 1,39–48 ] Very recently, the efficiency has been pushed to ≈18% owing to the development of novel NFAs (Y6 and derivatives) and efficient polymer donors. [ 49 ] Consequently, with the continuous development of efficient photoactive materials, significant progress has been achieved for flexible OSCs in recent years.…”