Growth, morphology and molecular orientation of controlled Indigo thin films on silica surfaces

Abstract

del Risorgimento, 4 -40136 Bologna (Italy) [b] Consiglio Nazionale delle Ricerche -Istituto per lo Studio dei Materiali Nanostrutturati (CNR-ISMN) via P. Gobetti 101, 40129 Bologna, Italy [c] Consiglio Nazionale delle Ricerche -Istituto per la Microelettronica e i Microsistemi (CNR-IMM) via P.

Bulk and Surface‐Mediated Polymorphs of Bio‐Inspired Dyes Organic Semiconductors: The Role of Lattice Phonons in their Investigation

“…Similarly, vapor films grown on various substrates [100] displayed a sharp single diffraction peak, which was taken as an indication of a crystalline texture with a preferential orientation, without however reporting to which polymorph it should be attributed. The issue has been clarified with the help of low-wavenumber Raman spectroscopy in a recent work [101] which provides new insight on the molecular arrangement of indigo on the substrate via the employment of a combination of techniques, confirming the key role of the extended network of intermolecular H-bonds in the growth of these systems. Figure 8 displays the AFM morphologies of three indigo films deposited in ultra-high vacuum conditions on Si/SiO 2 at different evaporation rates (10, 70 and 200 ng/min), alongside with their specular X-ray and Raman spectra.…”

Advances in applying C–H functionalization and naturally sourced building blocks in organic semiconductor synthesis

“…116 Since then significant efforts towards incorporating indigo in the organic electronics have emerged. 115,[117][118][119][120][121][122][123][124][125][126][127][128][129][130] Indigo has exhibited very promising semiconducting behaviors. It has balanced ambipolar charge transport, stemming from its reversible redox states and displays good charge mobility (1 Â 10 À2 cm 2 V À1 s À1 ).…”

“…115,117,118 Indigo thin films have been extensively used in OFET devices, organic inverters, and photodiode as active layers. [117][118][119][120][121] Indigo is electronic deficient and has been used as an non-fullerene acceptor in blends with the donor P3HT for use in OPVs. 122 Besides acting as a small molecule semiconductor itself, indigo is also an electron accepting building block in semiconducting D-A copolymers.…”

Precursor polymorph determines the organic semiconductor structure formed upon annealing

“…14 All elements of the class also exhibit extended polymorphism, with phases which are metastable in the processing conditions getting stabilized at surface growths or forming genuine thin film phases. [11][12][13]15,16 Among other pigment candidates as semiconductors, quinacridone (QA) has the peculiarity of possessing a molecular structure appearing like that of OSC pentacene, 17 where however the p conjugation on the molecular skeleton is broken by the substituents on the rings. Thus, similar to the case of indigo, 15 the solid-state assembly is driven both by the very strong intermolecular H-bonds due to the substituents and by the p stacking of neighboring molecules.…”

“…[11][12][13]15,16 Among other pigment candidates as semiconductors, quinacridone (QA) has the peculiarity of possessing a molecular structure appearing like that of OSC pentacene, 17 where however the p conjugation on the molecular skeleton is broken by the substituents on the rings. Thus, similar to the case of indigo, 15 the solid-state assembly is driven both by the very strong intermolecular H-bonds due to the substituents and by the p stacking of neighboring molecules. The interplay of interactions results for QA in the existence of four known polymorphs.…”