Electrochromism in titanyl and vanadyl phthalocyanine thin films

Abstract

The elect roc h rom ic be havi ou r of ti tany I p ht ha1 ocyan i ne [Ti (0) ( pc)] and vanady I p ht halocyan i ne [ V( 0)( pc)] t h i n films are reported. These materials manifest a reversible electrochromic change when reduced, but upon oxidation they show evidence of immediate destructive breakdown. The behaviour of the films is discussed in relation to the a-and p-phase structures of the films. It is found that the phase of [Ti(O)(pc)] changes during the electrochromic process owing to ion incorporation. This is the first report of an electrochromically induced phase change in metal phthalocyanine materials. The structure of the phase present in a metal phthalocyanine material is found to dictate whether or not it is electrochromic. If the structure is too closely packed to allow ion penetration, it will not be electrochromic. The implications of the irreversible oxidations are discussed in relation to the behaviour of metal bisphthalocyanine electrochromic materials.

Perchlorinated vanadyl tetrapyrazinoporphyrazine: spectral, redox and magnetic properties

“…27 Complexes with aluminum( iii ), gallium( iii ) and indium( iii ) show two reduction peaks, while vanadyl( iv ) complex has three reduction processes. This behavior is typical for vanadyl phthalocyanines and was also shown for aryloxy, alkyloxy and fluoroalkyloxy substituted phthalocyanine complexes [(( t -Bu) 2 C 6 H 3 O) 4 PcV IV O] and [(C 8 H 17 O) 4 PcV IV O] 37 and for [F 64 PcV IV O]. 38…”

Structures and Redox Characteristics of Electron-Deficient Vanadyl Phthalocyanines

“…Such facile movement of Li + in F 64 PcVO is favored by the bulky R f groups, since they hinder π−π stacking, which would lead to a tight solid-state packing and suppressed Li + migration, as seen, for example, in the β-phase of H 16 PcVO . For the latter, we calculate that there is no accessible space in the lattice, in contrast to the accessible voids in 1 and 2 .…”

“…The diminished R f -induced intermolecular interactions and the consequent loose packing in the solid state suggested opportunities for film formation, as well as the possibility of cation intercalation in interstitial spaces. Note that a tight packing, such as that observed for the β-phase of H 16 PcVO, prevents the intercalation of cations upon electrochemical reduction . The α-phase, in contrast, which is presumably less tightly packed, allows cation penetration and, thus, solid-state reductions that result in color changes upon reduction (electrochromic effect).…”

Voltammetric and spectroelectrochemical properties of titanylphthalocyanines bearing catecholato and naphthalenediolato moieties

“…The couple V has also considerable small peak current with respect to other peaks. The peak currents increased linearly with the square root of scan rates, for scan rates ranging from 0.010 to 0.500 V s À1 , indicating that the electrode reactions are purely diffusion-controlled for the couples III and VI [12,[16][17][18][19][20][21][22]. First oxidation process of the complex is split into two waves due to the aggregation of the complex during the positive potential scans.…”

“…Silver and his co-workers [21] studied the thin film voltammetric behavior of [Ti(O)(Pc)] complex. They showed that [Ti(O)(Pc)] complex coated on ITO electrode displayed two ring reduction processes and decompose during the oxidation process.…”