PTB7-Th
[CAS# 1469791-66-9]

Identification

• Classification: Catalysts and additives >> Polymer
• Name: PTB7-Th
• Synonyms: PCE-10; Poly([2,6'-4,8-di(5-ethylhexylthienyl)benzo[1,2-b;3,3-b]dithiophene]{3-fluoro-2[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl})
• Molecular Formula: (C₄₉H₅₇FO₂S₆)_n
• Molecular Weight: > 145000
• CAS Registry Number: 1469791-66-9
• SMILES: CCCCC(CC)CC1=CC=C(S1)C2=C3C=C(SC3=C(C4=C2SC(=C4)C5=C6C(=C(S5)C)C(=C(S6)C(=O)OCC(CC)CCCC)F)C7=CC=C(S7)C(CC)CCCC)C

Properties

• Solubility: soluble (chlorobenzene, dichlorobenzene)

Discovory and Applicatios

PTB7-Th, or Poly{4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl}, is a conjugated polymer widely recognized for its exceptional performance in organic photovoltaic (OPV) devices. It belongs to the family of donor-acceptor (D-A) polymers, which have emerged as a critical class of materials in the development of organic semiconductors. PTB7-Th has been extensively studied for its ability to achieve high power conversion efficiencies (PCEs) due to its advantageous structural, optical, and electronic properties.

The development of PTB7-Th was driven by the need for materials that combine efficient light absorption, tunable energy levels, and excellent charge transport. PTB7-Th is an improved derivative of the earlier polymer PTB7, with the introduction of a thiophene substituent at the benzo[1,2-b:4,5-b′]dithiophene (BDT) core. This modification enhances molecular packing, charge carrier mobility, and stability. The polymer’s fluorine atom on the thieno[3,4-b]thiophene unit contributes to a deeper highest occupied molecular orbital (HOMO) energy level, improving the open-circuit voltage of OPV devices.

PTB7-Th demonstrates strong absorption in the visible and near-infrared (NIR) regions, with a low bandgap of approximately 1.59 eV. This allows it to effectively harvest solar energy, making it an ideal donor material in bulk heterojunction (BHJ) solar cells. Its ability to form favorable morphologies with fullerene and non-fullerene acceptors enhances charge separation and reduces recombination losses, further boosting device efficiency.

Applications of PTB7-Th are centered on its use in OPVs. When paired with acceptor materials such as [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) or non-fullerene acceptors like ITIC, PTB7-Th-based solar cells have achieved PCEs exceeding 10%. This makes it one of the most successful polymers in OPV research. Moreover, its solution processability enables scalable manufacturing using techniques such as spin-coating and roll-to-roll printing.

Beyond OPVs, PTB7-Th has shown promise in other optoelectronic devices, including photodetectors and sensors. Its strong absorption and efficient charge transport make it suitable for detecting weak light signals and converting them into electrical responses. Research has also explored its potential in thermoelectric devices due to its semiconducting properties.

Despite its advantages, PTB7-Th faces challenges related to stability and cost. The polymer’s long-term operational stability under exposure to light, oxygen, and moisture requires further improvement for commercialization. Additionally, the synthesis of PTB7-Th involves multiple complex steps, contributing to its high production cost. Efforts are underway to develop cost-effective and environmentally friendly synthesis methods while enhancing its stability and performance.

In summary, PTB7-Th represents a significant milestone in the field of organic electronics, particularly for OPVs. Its unique combination of structural, electronic, and processing attributes has set a benchmark for high-performance polymer donors, paving the way for further advancements in sustainable energy technologies.