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Exploring the Intrinsic Piezofluorochromic Mechanism of TPE-An by STS Technique.

Jin S, Tian Y, Liu F, Deng S, Chen J, Xu N - Nanoscale Res Lett (2015)

Bottom Line: A theoretical calculation was carried out to find the relationship between the bandgap of TPE-An and the external force by combination of the classical tunneling theory and STS results.It is found that when the pressure variation on the surface of TPE-An film was increased to be over 4.38 × 10(4) Pa, the shrink of the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap can arrive at 1.1 eV.It is concluded that the piezofluorochromic behaviors of TPE-An should originate from the shrinking effect of the bandgap under external force.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, 510275, People's Republic of China.

ABSTRACT
9,10-bis(4-(1,2,2-triphenylvinyl)styryl)anthracene (TPE-An) materials have attracted considerable attention in recent years because they have high luminescence efficiency and excellent piezofluorochromic properties, which have potential applications in organic light-emitting display (OLED) area. Scanning tunneling spectroscopy (STS) technique was used to study the piezofluorochromic mechanism of aggregation-induced emission (AIE) materials for the first time. Photoluminescence (PL) experiments revealed that the emission peak of TPE-An is observed to exhibit a red-shift with the increase of the grinding time. A theoretical calculation was carried out to find the relationship between the bandgap of TPE-An and the external force by combination of the classical tunneling theory and STS results. It is found that when the pressure variation on the surface of TPE-An film was increased to be over 4.38 × 10(4) Pa, the shrink of the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap can arrive at 1.1 eV. It is concluded that the piezofluorochromic behaviors of TPE-An should originate from the shrinking effect of the bandgap under external force. Moreover, this research method may shed light on comprehending and adjusting the piezofluorochromic characters of other AIE materials.

No MeSH data available.


Related in: MedlinePlus

a The relationship among the red-shift of PL peak, the HOMO-LUMO gap variation, and the applied pressure variation. The inset is the surface deformation of TPE-An film suffered from the electrostatic force in STS experiments. b A schematic illustration of the piezofluorochromic behaviors of TPE-An materials by the band model
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Fig6: a The relationship among the red-shift of PL peak, the HOMO-LUMO gap variation, and the applied pressure variation. The inset is the surface deformation of TPE-An film suffered from the electrostatic force in STS experiments. b A schematic illustration of the piezofluorochromic behaviors of TPE-An materials by the band model

Mentions: The relationship among the red-shift of PL peak, the HOMO-LUMO gap variation, and the applied pressure variation is shown in Fig. 6a. It is seen in Fig. 6a that the red-shift extent of the PL peak turns larger with the decrease of the HOMO-LUMO gap. It is also found that the red-shift extent of the PL peak will increase with the pressure of external force. To better understand the piezofluorochromic mechanism of TPE-An sample, the inset gives the schematic diagram of TPE-An sample suffered from the electrostatic force, in which one can see that an obvious deformation occurs on the surface under external force. Figure 6b gives the surface energy-band diagram of TPE-An under external force (compressive force or electrostatic force). As shown in Fig. 6b, the HOMO-LUMO gap of TPE-An decreases with the increase of the compressive force or the electrostatic force. Correspondingly, the wavelength λ of emission light turns larger with the shrink of the HOMO-LUMO gap, which causes the red-shift of PL peak in Fig. 1.Fig. 6


Exploring the Intrinsic Piezofluorochromic Mechanism of TPE-An by STS Technique.

Jin S, Tian Y, Liu F, Deng S, Chen J, Xu N - Nanoscale Res Lett (2015)

a The relationship among the red-shift of PL peak, the HOMO-LUMO gap variation, and the applied pressure variation. The inset is the surface deformation of TPE-An film suffered from the electrostatic force in STS experiments. b A schematic illustration of the piezofluorochromic behaviors of TPE-An materials by the band model
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4558996&req=5

Fig6: a The relationship among the red-shift of PL peak, the HOMO-LUMO gap variation, and the applied pressure variation. The inset is the surface deformation of TPE-An film suffered from the electrostatic force in STS experiments. b A schematic illustration of the piezofluorochromic behaviors of TPE-An materials by the band model
Mentions: The relationship among the red-shift of PL peak, the HOMO-LUMO gap variation, and the applied pressure variation is shown in Fig. 6a. It is seen in Fig. 6a that the red-shift extent of the PL peak turns larger with the decrease of the HOMO-LUMO gap. It is also found that the red-shift extent of the PL peak will increase with the pressure of external force. To better understand the piezofluorochromic mechanism of TPE-An sample, the inset gives the schematic diagram of TPE-An sample suffered from the electrostatic force, in which one can see that an obvious deformation occurs on the surface under external force. Figure 6b gives the surface energy-band diagram of TPE-An under external force (compressive force or electrostatic force). As shown in Fig. 6b, the HOMO-LUMO gap of TPE-An decreases with the increase of the compressive force or the electrostatic force. Correspondingly, the wavelength λ of emission light turns larger with the shrink of the HOMO-LUMO gap, which causes the red-shift of PL peak in Fig. 1.Fig. 6

Bottom Line: A theoretical calculation was carried out to find the relationship between the bandgap of TPE-An and the external force by combination of the classical tunneling theory and STS results.It is found that when the pressure variation on the surface of TPE-An film was increased to be over 4.38 × 10(4) Pa, the shrink of the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap can arrive at 1.1 eV.It is concluded that the piezofluorochromic behaviors of TPE-An should originate from the shrinking effect of the bandgap under external force.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, Sun Yat-sen University, Guangzhou, 510275, People's Republic of China.

ABSTRACT
9,10-bis(4-(1,2,2-triphenylvinyl)styryl)anthracene (TPE-An) materials have attracted considerable attention in recent years because they have high luminescence efficiency and excellent piezofluorochromic properties, which have potential applications in organic light-emitting display (OLED) area. Scanning tunneling spectroscopy (STS) technique was used to study the piezofluorochromic mechanism of aggregation-induced emission (AIE) materials for the first time. Photoluminescence (PL) experiments revealed that the emission peak of TPE-An is observed to exhibit a red-shift with the increase of the grinding time. A theoretical calculation was carried out to find the relationship between the bandgap of TPE-An and the external force by combination of the classical tunneling theory and STS results. It is found that when the pressure variation on the surface of TPE-An film was increased to be over 4.38 × 10(4) Pa, the shrink of the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap can arrive at 1.1 eV. It is concluded that the piezofluorochromic behaviors of TPE-An should originate from the shrinking effect of the bandgap under external force. Moreover, this research method may shed light on comprehending and adjusting the piezofluorochromic characters of other AIE materials.

No MeSH data available.


Related in: MedlinePlus