ABSTRACT
Ultralong organic phosphorescence (UOP) materials have attracted considerable attention in recent years. Herein, a new type of flexible films is fabricated by doping amphipathic pyrene tetrasulfonic acid sodium salts into amorphous poly(vinyl alcohol) matrix, which enables the realization of color-tunable UOP spanning from orange-red to green after excitation light is switched off. Interestingly, precise control of the proportion of isolated-molecular and aggregated-state phosphorescence is demonstrated for colorful afterglow using photo-activation. An increase in the dynamic phosphorescence lifetime of isolated molecules is observed from 894.75 to 1735.71 ms following an 8 min irradiation under ambient conditions. The photo-activation, however, showed little influence on aggreated-state phosphorescence. This flexible and processable film exhibits versatile applications in multicolor afterglow displays, ultraviolet detection, multilevel information encryption, etc. This study not only provides a strategy for the rational regulation of UOP colors but also expands the application potential of color-tunable UOP materials.
ABSTRACT
A series of monomers containing tetraphenylsilane connected to different thiophenes such as thiophene, bithiophene and terthiophene were designed and synthesized and were further used to prepare the corresponding polymers via electrochemical polymerization (pSiTPTP, pSiTPBTP and pSiTPTTP). From the polymers, the effective conjugate elements were well defined as bithiophene, quaterthiophene and sexithiophene because the sp3 Si atom can block the conjugation between the thiophene units in the polymer backbone. The spectroelectrochemical results indicated that pSiTPTP is incapable of electrochromism, which may be attributed to the insufficient conjugation length of the independent bithiophene. In contrast, both pSiTPBTP and pSiTPTTP exhibited obvious electrochromic properties and furthermore, pSiTPTTP displayed a shorter switching time and better stability. Such different electrochemical behaviors can be ascribed to the looser stacking structure and lower oxidation potential of pSiTPTTP with the independent sexithiophene unit. The EIS measurements also confirmed the lower charge-transfer resistance and higher ion-diffusion rate of pSiTPTTP with the independent sexithiophene unit. Hence, we can conclude that the effects of the electrochromic behavior of the conjugation-broken polythiophene derivatives depend on the increased conjugation length of the thiophene repeating unit, in which the inadequate electrochromism with bithiophene units can change to superior electrochromic properties with increased sexithiophene units.
ABSTRACT
Correction for 'Multi-color electrochromism from coordination nanosheets based on a terpyridine-Fe(ii) complex' by Yu Kuai et al., Dalton Trans., 2019, DOI: 10.1039/c9dt02980j.
ABSTRACT
A metal complex nanosheet was synthesized by the liquid-liquid interface self-assembly method from a star-shaped ligand of tris[4-(4'-2,2':6',2''-terpyridyl)-phenyl]amine in organic solvents and metal ion Fe(ii) in water solution. The as-prepared nanosheet possessed excessively smooth morphology with a thickness of hundreds of nanometers. Adhering to an ITO glass, the nanosheet showed noticeable electrochromism from purplish red at 0 V to orange-yellow at 1.4 V and green at 1.6 V. Besides, the nanosheet exhibited outstanding stability with the optical contrast maintained at almost 100% of its original electrochemical activity over 500 cycles. The liquid-liquid interface self-assembly method was proven to be promising to prepare a polymeric metal complex for potential electrochromic applications.
ABSTRACT
A star-shaped thiophene derivative, namely PHBT, consisting of one central core of phenyl and three arms of bithiophene, was newly synthesized and characterized, in order to further investigate the relationship between the star-shaped monomer structure (central core and peripheral arm) and the polymeric electrochromic properties. Then it was further successfully prepared into the corresponding cross-linked polymer pPHBT via electrochemical polymerization. After applying positive voltage, pPHBT exhibited excellent electrochromic properties with surprising multi-color changes between three colors, orange-yellow, green and blue, and a fast color switching speed. Furthermore, electronic structure, cyclic voltammetry and electrochromic results of pPHBT can contribute much to explain the electrochromic behavior of pTPABT with the triphenylamine core and the quadruple thiophene arm. The electrochromism of pTPABT might consist of two parts derived from the oxidative states of triphenylamine and quadruple thiophene groups, respectively. This offers a new insight into the electrochromism mechanics of conjugated polymers.
ABSTRACT
A novel strategy to obtain rapid electrochromic switching response by introducing 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) moiety into polytriphenylamine backbone has been developed. The electrochromic properties of the integrated polymer film are investigated and a possible mechanism is proposed with TEMPO as a counterion-reservoir group to rapidly balance the charges during electrochromic switching, which leads to significantly improved electrochromism performance.
