Investigation of charge transport in the molecular photodiode consisting of ferrocene/flavin/viologen/TCNQ molecular heterojunction

Kyung Sang Cho, Yun Suk Nam, Jeong Woo Choi, Won Hong Lee, Jinhoon Choi, Nam Woong Song, Dongho Kim

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


A molecular photodiode with the hetero-Langmuir-Blodgett (LB) film consisting of an electron donor (D), sensitizer (S), relay (R), and acceptor (A) was fabricated. Ferrocene octadecyl amine (Ferrocene), 7,8-dimethyl-10-dodecyl isoalloxazine (flavin), N-Allyl-N′-[3-propylamido-N″,N″-di(n-octadecyl)]-4,4′ -bipyridium dibromide (viologen) and N-docosilquinolinium tetracyanodimethan (TCNQ) were used as the D, S, R, and A units, respectively. By aligning the hetero-LB film of the D/S/R/A units on indium tin oxide (ITO) coated glass with an aluminum thin film, a molecular photodiode with a Metal/Insulator/Metal (MIM) structure was constructed. The decay of the transient photocurrent of MIM device was measured using a 355 nm Nd:YAG pulse laser as the light source and the charge transfer rate was obtained. The charge transfer rate was faster in the D/S/R/A heterojunction than in S/R and S/R/A heterojunction devices due to less recombination from the A to S and less back electron transport due to the existence of D molecules. Various effects such as the LB film thickness, interface structure, and Schottky barrier on the charge transfer rate were investigated. The results showed that the charge transport efficiency of the molecular photodiode became higher when the LB film thickness increased and the head/head interfaced structure of the S/R hetero LB films was adopted. Furthermore, improvement of the molecular device efficiency occurred when spacer molecules were adopted between the electrode and the LB film.

Original languageEnglish
Pages (from-to)93-99
Number of pages7
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Issue number1
Publication statusPublished - 2002 Mar 26

Bibliographical note

Funding Information:
This work was supported by grants from Korea Science and Engineering Foundation (KOSEF: 98-0502-08-01-3) and National Creative Research Initiatives of the Ministry of Science and Technology of Korea. The authors appreciate the advice of Dr S. Isoda, S. Ueyama, and K. Akiyama in Mistsubishi Electronic Corporation Central Research Laboratory.

All Science Journal Classification (ASJC) codes

  • Surfaces and Interfaces
  • Physical and Theoretical Chemistry
  • Colloid and Surface Chemistry


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