PBDB-T-2Cl
[CAS# 2239295-71-5]

Identification

• Classification: Catalysts and additives >> Polymer
• Name: PBDB-T-2Cl
• Synonyms: PCE14; Poly[[4,8-bis[5-(2-ethylhexyl)-4-chloro-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c']dithiophene-1,3-diyl]-2,5-thiophenediyl]
• Molecular Formula: (C₆₈H₇₆C₁₂O₂S₈)_n
• Molecular Weight: >50000
• CAS Registry Number: 2239295-71-5
• SMILES: C1(=C9C(=C(C2=C1C=C(S2)C)C3=CC(=C(S3)CC(CC)CCCC)Cl)C=C(C8=CC=C(C5=C7C(=C(C4=CC=C(S4)C)S5)C(C6=C(SC(=C6C7=O)CC(CC)CCCC)CC(CC)CCCC)=O)S8)S9)C%10=CC(=C(S%10)CC(CCC)CC)Cl

Properties

• Solubility: soluble (chlorobenzene,chloroform)
• Melting point: > 200 °C

Discovery and Applications

PBDB-T-2Cl is a chlorinated polymer donor material that has emerged as a significant development in the field of organic photovoltaics (OPVs). As a derivative of PBDB-T, it incorporates chlorine atoms into its molecular structure to enhance its electronic and optical properties. This fine-tuning has made PBDB-T-2Cl a prominent choice for achieving high power conversion efficiencies (PCEs) in polymer solar cells (PSCs), particularly in conjunction with non-fullerene acceptors.

PBDB-T-2Cl was developed through strategic molecular engineering to address the limitations of earlier polymer donors. By introducing two chlorine atoms onto the benzodithiophene-thieno[3,4-b]thiophene backbone, researchers achieved a polymer with improved light absorption, reduced bandgap, and higher charge-carrier mobility. These characteristics contribute to more efficient charge separation and transport, essential for high-performance solar cells.

The chlorination of PBDB-T-2Cl enhances the intermolecular interactions, improving the material's crystallinity and morphology. These features ensure optimal phase separation and strong π-π stacking, leading to an efficient active layer in OPVs. Furthermore, the chlorine atoms influence the energy levels, fine-tuning the material's HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) to better match the energy levels of various non-fullerene acceptors. This compatibility reduces energy losses during charge transfer and improves overall device efficiency.

PBDB-T-2Cl has found widespread application in OPVs, particularly in all-polymer solar cells (all-PSCs) and bulk-heterojunction (BHJ) devices. When paired with acceptor materials such as Y6 or ITIC derivatives, PBDB-T-2Cl demonstrates outstanding PCEs, often exceeding 17%, making it a benchmark polymer donor in the field. Its ability to form stable and efficient active layers contributes to its appeal for commercial applications.

In addition to its high efficiency, PBDB-T-2Cl exhibits excellent thermal stability and operational durability, which are crucial for the long-term performance of solar cells. Its robust morphology and resistance to phase separation over time ensure consistent device operation under real-world conditions. These properties position PBDB-T-2Cl as a strong candidate for integration into commercial OPV modules.

However, challenges remain in scaling up the synthesis of PBDB-T-2Cl and optimizing its environmental footprint. Research is ongoing to develop cost-effective and sustainable production methods while maintaining its high performance. Additionally, studies aim to enhance the compatibility of PBDB-T-2Cl with various acceptor materials to further broaden its application range.

PBDB-T-2Cl represents a milestone in polymer donor design, combining structural simplicity with outstanding performance metrics. Its role in advancing the efficiency and stability of OPVs highlights its importance in renewable energy technologies.

References

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