Order Code: B271
MSDS sheet


(excluding Taxes)


General Information

CAS number
Chemical formula C9H6S2
Molecular weight 178.27 g/mol


  • 4H-Cyclopenta[2,1-b:3,4-b']dithiophene
  • 4H-Thieno[3',2':4,5]cyclopenta[1,2-b]thiophene
  • 3,4-Dithia-7H-cyclopenta[a]pentalene
  • CPDT
Classification / Family Monomers, Building blocks, Heterocycles, Chemical synthesis for low-band gap polymers, Thiophene, Intermediates for high performance Organic Photovoltaics, OFETs, Polymer solar cells


Product Details

Purity >99%
Melting point 71.0 to 75.0°C
Color Off-white powder


Chemical Structure

Chemical structure of 4H-Cyclopenta[2,1-b:3,4-b']dithiophene CAS number 389-58-2
Chemical structure of 4H-Cyclopenta[2,1-b:3,4-b']dithiophene.



4H-cyclopenta[2,1-b:3,4-b′]dithiophene, also known as CPDT, a rigid coplanar structure favouring π−π intermolecular interactions with good electron-donating properties, has been one of the most attractive building blocks for organic field effect transistors and organic electronics. The five-member ring in the middle also offer the function to have side-chain manipulation to enhance solubility in solutions for device fabrications, morphology and polymer processing. One of the intensively studied polymer for organic electrons, PCPDTBT, with the alternating CPDT and 2,1,3- benzothiadiazole (BT) units, has demonstrated device performance of PCE over 6% [5]

Recently, CPDT backboned polymer CPE-K has been incorporated as the hole transporting layer (HTL) in polymer/fullerene BHJ and provskite solar cells. The devices using CPE-K HTL show competitive performance compared with that using PEDOT:PSS HTL. As an alternative to PEDOT:PSS, the use of CPE-K as an organic hole transport material enables the formation of uniform perovskite films with complete surface coverage for an efficient, stable perovskite/fullerene planar heterojunction solar cell [1, 2]

4H-cyclopenta[2,1-b:3,4-b′]dithiophene is the intermediate for the synthesis of 4,4'-alkyl-cyclopenta[2,1-b:3,4-b′]dithiophene [6].

synthesis of 4,4'-alkyl-cyclopenta[2,1-b:3,4-b′]dithiophene
Synthesis of 4,4'-alkyl-cyclopenta[2,1-b:3,4-b′]dithiophene in aqueous solutions.


NMR Characterisation


1H NMR cyclopenta-bithiophene
1H NMR spectrum of 4H-Cyclopenta[2,1-b:3,4-b']dithiophene in CDCl( view full version)

Literature and Reviews

  1. Conjugated polyelectrolyte hole transport layer for inverted-type perovskite solar cells, H. Choi et al., Nat. Commun., DOI: 10.1038/ncomms8348, 6, 7348 (2015)
  2. Conductive conjugated polyelectrolyte as hole-transporting layer for organic bulk heterojunction solar cells, H. Zhou, et al., Adv. Mater. , 26, 780–785(2014)
  3. Improved Photovoltaic Performance of a Semicrystalline Narrow Bandgap Copolymer Based on 4H-Cyclopenta[2,1-b:3,4- b′]dithiophene Donor and Thiazolo[5,4-d]thiazole Acceptor Units, S. V. Mierloo et al., Chem. Mater., 24, 587−593 (2012).
  4. Synthesis and characterization of a series of low-bandgap copolymers based on cyclopenta[2,1-b:3,4-b']dithiophene and thienopyrroledione for photovoltaic applications, Y-R. Hong et al., Solar Energy Materials & Solar Cells 102, 58–65 (2012)
  5. Alternating Copolymers of Cyclopenta[2,1-b;3,4-b´]dithiophene and Thieno[3,4-c]pyrrole-4,6-dione for High-Performance Polymer Solar Cells, Z. Li, et al., Adv. Func. Mater., 21, 3331–3336(2011)
  6. Highly efficient and facile alkylation of 4Hcyclopenta-[2,1-b:3,4-b0]dithiophene in water, T. B. Raju et al., RSC Adv., 4, 37738 (2014).