A low-cost miniaturized colorimetric sensor with vertically-stacked semi-transparent finger-type organic photo detector for formaldehyde sensing

Ching Fu Lin, Hsiao Wen Zan, Chia Jung Lu, Hsin Fei Meng, Olivier Soppera

Research output: Contribution to journalArticle

1 Citation (Scopus)


We proposed a sensitive colorimetric sensing system using a paper-like sensing layer on top of a vertically stacked finger-type organic photodetector (OPD) and commercial light-emitting diode (LED). The stacked OPD/LED device was small, with an area of 0.8 cm × 0.5 cm that was even smaller than a coin. Using commercial colorimetric formaldehyde (HCHO) sensing molecules to form the sensing layer, the stacked detecting system successfully detected HCHO of concentrations ranging from 40 to 1000 ppb within 20 min. Critical parameters affecting the sensitivity were investigated. The final system exhibited a stable calibration curve over 60 days. The long lifetime was attributed to using 2,6-Bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene (PBDTTT-C-T): phenyl-C71-butyric acid methyl ester (PC71BM) to serve as a blended system and using the current variation ratio to represent the sensing response.

Original languageEnglish
Pages (from-to)115-121
Number of pages7
JournalOrganic Electronics
Publication statusPublished - 2019 Oct



  • Colorimetric-type sensing
  • Finger type
  • Formaldehyde sensing
  • Organic photodetector
  • Vertically integrated

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Chemistry(all)
  • Condensed Matter Physics
  • Materials Chemistry
  • Electrical and Electronic Engineering

Cite this