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

对玻璃基板进行HF处理后，在NO_2环境下，在150℃的工作温度下，厚度为200 nm的酞菁铜薄膜表现出良好的气体响应特性。然而，从实际应用的角度来看，还存在一些问题。超薄薄膜的制备是解决这些问题的方法之一。薄膜厚度的减小有望带来更快的气体响应和改善的采收率特性。同时，还可能引起气敏性的降低。氟铝酞菁（AlFPc）分子具有线性主链（Al-F）_x，被一堆平面Pc环包围，这可能导致高导电性的极薄薄膜。在真空10^<-4> Pa范围内，采用真空升华法在未处理的玻璃基板上沉积了厚度为10 ~ 20nm的AlFPc薄膜。薄膜显示出足够的电导率，如预期的那样用于实际气体传感器元件…更多。1 ppm NO_2气体掺杂和脱掺杂循环的气体响应特性也表明，即使在80℃的操作温度下，也具有较高的气敏性、较快的响应速度和良好的回收特性。这些结果可以通过AlFPc分子在膜中的特定排列和NO_2气体分子在膜中的扩散减少来解释。因此，基于AlFPc分子的极薄薄膜是一种具有实际应用前景的薄膜型NO_2气体元件材料。为了制备取向性更高的极薄膜，取代了AlFPc分子，合成了氟铝四叔丁基酞菁（AlFPc(C_4/H_9)_4）和氟铝八甲基酞菁（AlFPc(CH_3)_8）。由于两种分子都被不对称基团所取代，它们可能在真空升华薄膜中形成更特殊的阵列。此外，取代基对AlFPc大环的给电子作用可能改善了气体响应特性。事实上，两种取代AlPcF分子的真空升华极薄膜都表现出改善的NO_2气体响应特性。结果还表明，AlFPc分子的替代是实现实用的薄膜NO_2气体传感器的另一种途径。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