Fabrication and practical application of metallo-phthalocyanine thin film-based NO_2 gas sensor

玻璃衬底经过HF处理后，在150℃的NO2气氛中，厚度为200 nm的铜酞菁薄膜表现出了良好的气体响应特性。然而，从实际使用的角度来看，还存在一些问题。超薄膜的制备是解决这一问题的方法之一。薄膜厚度的减小有望带来更快的气敏响应和更好的采油特性。同时，可能会导致气体敏感性的降低。用真空升华法在未处理的玻璃衬底上制备了厚度为10~20 nm的AlFPc薄膜。如预期的那样，薄膜显示了足够的导电性，可以用于实际的气体传感器元件…更多。1ppm NO2气体掺杂和脱掺杂循环的气体响应特性也表现出较高的气体灵敏度、较快的响应速度和较好的恢复特性，即使在80℃的工作温度下也是如此。这些结果可以用膜中AlfPc分子的特殊排列和NO2气体分子向膜内扩散的减少来解释。因此，基于AlFpc分子的超薄膜材料是一种具有实际应用前景的薄膜材料。为了制备更高取向的超薄膜，取代AlFpc分子，合成了氟铝四丁基酞菁(Alfpc(C4/H9)4)和氟铝八甲基酞菁(Alfpc(CH3)8)。由于这两个分子都被不对称基团取代，它们可能会在真空升华薄膜中形成更特殊的阵列。此外，由于取代基对AlFPc大环的供电子作用，可能会改善气体响应特性。事实上，基于这两个取代AlPcF分子的真空升华非常薄的薄膜已经显示出改善的NO2气体响应特性。研究结果还表明，AlFpc分子的替代是实现实用化的薄膜NO2气体传感器的另一种途径。较少

Copper phthalocyanine thin films with the thickness of 200 nm have shown good gas response characteristics in the NO_2 ambience at the operation temperature of 150 ℃, after the HF treatment of glass substrates. However, there are still some problems from the viewpoint of practical uses. Fabrication of very thin film is one of the methods to solve them. Reduction in the thickness of film is expected to lead a faster gas response and improved recovery characteristics. At the same time, reduction in the gas sensitivity may be caused. Fluoroaluminum phthalocyanine (AlFPc) molecules have a linear backbone (Al-F)_x surrounded by a stack of planar Pc rings, which may result in a high conductive very thin film.The AlFPc films with the thickness of 10 to 20 nm have been deposited on the non-treated glass substrate by using a vacuum sublimation method in the vacuum of 10^<-4> Pa range. The films have revealed an enough electric conductivity for the use of practical gas sensor element as expected … More . The gas response characteristics for the cycle of doping and dedoping of 1 ppm NO_2 gas have also showed the high gas sensitivity, the faster response rate and the good recovery characteristics even at the operation temperature of 80 ℃. These results can be interpreted by the specific array of the AlFPc molecules in the film and the decrease in diffusion of NO_2 gas molecules into the film. As a result, the very thin film based on AlFPc molecules is a promising material for the practical application to thin film-based NO_2 gas element.In order to fabricate a more highly oriented very thin film, substituted AlFPc molecules, fluoroaluminum tetra-t-butyl-phthalocyanine (AlFPc(C_4/H_9)_4) and fluoroaluminum octa-methyl-phthalocyanine (AlFPc(CH_3)_8) have been synthesized. Since both molecules have been substituted by the asymmetric groups, they may cause more specific arrays in the vacuum sublimed thin films. Furthermore, the substituted groups may improve the gas response characteristics due to their electron-donating effect on the AlFPc macrocycles. Indeed, the vacuum sublimed very thin films based on both substituted AlPcF molecules have shown the improved NO_2 gas response characteristics. The results also suggest that the substitution of AlFPc molecules is another approach to realize the practical thin film-based NO_2 gas sensors. Less