Photo-physics of PTB7, PCBM and ICBA based ternary solar cells

Ramakant Sharma, Hyunwoo Lee, Vinay Gupta, Hoyeon Kim, Mahesh Kumar, Chhavi Sharma, Suresh Chand, Seunghyup Yoo, Dipti Gupta

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

Indene-C60bisadduct (ICBA) is one of the rare acceptors which can supersede commonly used phenyl-C71-butyric acid methyl ester (PCBM70) in enhancing the performance of bulk heterojunction (BHJ) solar cells owing to its shallower lowest unoccupied molecular orbital (LUMO) level. However, ICBA tends to decrease the photocurrent for most of the low band-gap polymers synthesized to date. Here we examine the interaction of ICBA with the one of the popular low band-gap polymers poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl) carbonyl] thieno[3,4-b]thiophenediyl]] (PTB7), at femtosecond level, to explore key dynamics governing the operation of BHJ cells involving ICBA. The photo-physics of binary and ternary systems based on PTB7 coupled with PCBM70 and/or ICBA are studied by means of transient absorption spectroscopy (TAS) and electrochemical impedance spectroscopy (EIS) and supported by morphology analysis. Our study suggests that both inefficient charge-separation and poor charge transport of ICBA is responsible for relatively low photocurrent generation.

Original languageBritish English
Pages (from-to)111-117
Number of pages7
JournalOrganic Electronics
Volume34
DOIs
StatePublished - 1 Jul 2016

Keywords

  • Carrier concentration
  • Electrochemical impedance spectroscopy
  • ICBA
  • PCBM
  • PEIE
  • PTB7
  • Transient absorption spectroscopy
  • Trap

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