An Indium Synthetic Etioporphyrin for Organic Electronics: Aggregation and Photoconductivity in Thin Films

Abstract

A new complex of indium(III)chloride with etioporphyrin-I was synthesized and characterized. As with naturally occurring extraligated etioporphyrins, the InCl-EtioPÀ I spectrum in solution has a very strong B-band and a more than an order of magnitude weaker Q-band, but this difference diminishes in solid films of InCl-EtioPÀ I obtained by thermal evaporation in vacuum. In a solid, molecules have a tight convex-convex arrangement in a 2D double layered structure with interplane distance of 3.066 Å. The conductivity of films can easily be activated by the action of temperature or light. In the cells with symmetrical lateral contacts the photocurrent exceeds the dark current by about three orders of magnitude, with the contribution of photons in the Q-band range being greater than expected from the experimental or calculated absorption spectrum. The Q-bands contribute significantly to the photovoltaic effect in the ITO/InCl-EtioPÀ I/Al sandwich cells. Such cells show an untypically strong signal in the photodiode regime, which yields the spectral detectivity of 10^12 Jones.

Molecular And Solid‐State Structure Of Oxovanadium(IV) Etioporphyrin‐III

“…The spectrum consists of a weak broad band close to the UV edge of the visible, a very large and narrow Soret-band peaked at 408 nm, and a doublet of weak Q-bands at 532/570 nm. [2,31,42] In the solutions of the stock VO-EtioP-III compound studied in Ref. [23] the narrow band appearing at 414 nm was also identified by the authors as the Soret band (absorption in the range from 200 to 270 nm was due to the acetone solvent), and two much smaller bands at 530 and 569 nm were assigned to Q-bands.…”

“…In the Cu‐EtioP‐III crystals the interplane distance is even shorter, but dimers are not formed, either. Recently, we reported the crystal structure of another synthetic extraligated complex, indium(III) chloride etioporphyrin‐I, which shows a double layer, but not dimeric, motif of convex‐convex packed molecules with interplane distance of 3.07 Å [31] …”

“…Solutions in common organic solvents, such as chloroform, toluene, hexane or mineral oils have a purple color and obey the Beer law (Figure S7, S8). The spectrum consists of a weak broad band close to the UV edge of the visible, a very large and narrow Soret‐band peaked at 408 nm, and a doublet of weak Q‐bands at 532/570 nm [2,31,42] . In the solutions of the stock VO‐EtioP‐III compound studied in Ref.…”

“…match well with what happens in Figure 4 and S6, their proposed geometrical model is not suitable for solid VO‐EtioP‐III. The redshift of the absorption bands is commonly attributed to the formation of J‐aggregates, [22,24,31,35,38] in which molecular chromophores are oriented “head‐to‐tail” or, most often, in a “brick wall” pattern, i. e . are slipped along the long axis by about half the molecular length or more.…”

“…Recently, we reported the crystal structure of another synthetic extraligated complex, indium(III) chloride etioporphyrin-I, which shows a double layer, but not dimeric, motif of convex-convex packed molecules with interplane distance of 3.07 Å. [31] The most remarkable feature of the VO-EtioP-III is a short distance between the axial oxygen of one molecule and the hydrogen atoms in the methyl group (2.60 Å), methylene group (2.63 Å) and meso-C (2.68 Å) of another molecule -Figure 2(a). This may indicate formation of an intermolecular hydrogen bond, which could be a dominant supramolecular synthon.…”