A new series of sandwich-like lanthanide doping bis[2,3,9,10,16,17,23,24-octakis (octyloxy) phthalocyaninato] complexes Ln[Pc*]2 (Pc*=Pc(OC8H17)8, Ln=Sm, Pr, Er) were used as NO2 gas-sensing materials is described in the article. The gas-sensing films of Ln[Pc*]2 were prepared by Langmuir-Blodgett (LB) technique and the NO2 gas-sensing properties of Ln[Pc*]2 LB films were studied. The sensitive properties of Ln[Pc*]2 LB films to NO2 gas was monitored by the change of conductivity during gas exposure. Therein, Sm[Pc*]2 has the best sensitivity and responsivity to NO2 gas. The detecting range is from 0~100ppm, and the response and recovery time of 11-layer Sm[Pc*]2 LB film to 20ppm NO2 at room temperature is 16 s and 80 s, respectively. The thinner the film, the faster the response and recovery become. Recovery time in air is longer than that in pure N2.

Langmuir–Blodgett (LB) films of general organic semiconductor materials may be used as gas sensors because the conductivity depends on the presence of some gas species. Praseodymium bis [phthalocyaninato] complex-based LB films are very sensitive to the change of nitrogen dioxide (NO2) gas concentration. In the paper, a new kind of sandwich-like praseodymium bis[2,3,9,10,16,17,23,24-octakis (octyloxy) phthalocyaninato] complex Pr[Pc ]2 (Pc% Pc(OC8H17)8) was used as film-forming material. It is found that a mixture of Pr[Pc ]2 and octadecanol (OA) with 1:6 molar ratio formed an excellent material for the fabrication of gas-sensing LB film. The sensitive property of Pr[Pc ]2 LB films to NO2 gas was monitored by the change of resistance during gas exposure. The detecting range was from 0 to 100 ppm, and the response time of 11-layer Pr[Pc ]2 LB film to 20 ppm NO2 was 27 s at room temperature. Factors affecting gas-sensing properties of Pr[Pc ]2 LB films to NO2 gas such as temperature, number of film layers and processing conditions were also discussed in the paper.

Microsensor for nitrogen dioxide (NO2) fabricated by Langmuir–Boldgett (LB) films of Samarium bisw2,3,9,10,16,17,23,24-octakis (octyloxy)phthalocyaninatox complex SmwPc*x2 (Pc*sPc(OC8H17)8) and charge-flow transistor (CFT) are evaluated. Pure SmwPc*x and mixture of SmwPc*x and octadecanol (OA) deposited from both pure water and 10y4 M Cd2q subphases were 22 investigated. It is found that a mixture of 1:3 SmwPc*x2:OA forms an excellent material for the fabrication of gas-sensing LBfilm by studying the film-forming characteristic. Such novel microsensor has been fabricated by incorporating the multilayer LBfilm into the gate electrode of a metal-oxide-semiconductor field effect transistor, forming an array of CFT. On the application of a gate voltage (VGS), greater than the threshold voltage (VTH), a delay was observed in the response of the drain current. It is due to the time taken for the resistive gas-sensing film to charge up to VGS. This delay characteristic was found to depend on the concentration of NO2. Results are presented showing that the device can detect reversibly concentration of NO2 gas down to 5 ppm at room temperature.

Pm-e polyaniline (PAN) fihn, polyaniline and acetic acid (AA) mixed fihn, as well as PAN and polystyrenesalfonic acid (PSSA) composite fihn with various nmnber of layers were prepared by Langmuir Blodgett (LB) and selassembly (SA) techniques. These ultra thin fihns were characterized by ultraviolet visible (UV VIS) spectroscopy mid allipsometry, it is fomld tbat the tbickness of PAN based ultra thin fihns increases linearly with the increase of the number of fihn layers. The gas sensitivity of these ultra tbin fihns with vmious layers to NO2 was smdiedi it is fomld tbat pm-e polymliline fihns prepared by LB technique had good sensitivity to NO2, while SA fihns exhibited faster recovery property. The response time to NO2 mid the relative chmlge of resistmlce of ultra tbin fihns increased with the increase of the number of fihn layers. The response time of three layer PAN fihn prepared by LB technique to 20 ppm NO2 was about 10s, two layer SA fihn was about 8s. The mechmlism of sensitivity to NO2 of PAN based ultra thin fihns was also discussed.

A new ldnd of sandwich like bis[2,3,9,10,16,17,23,24 octalds (octyloxy) pbtbMocyaninato] rare earth complexes RE[Pc*]2 (Pc*Pc(OCaH17)8, RE Sm, Pr, Er) are used to fihn fomling materiM. Pure RE[Pc*]2 and mixture of RE[Pc*]2 mid auxiliary fihn foianing solvents stearic acid (SA) mid octadecmlol (OA) deposited from both pure water and 10 4M Cd2+ subphases are investigated, it is fomld tlaat a mixture of Sm[Pc*]2 mid OA forms ml excellent material for the fabrication of gas sensing LB fihn by studying the fihn foianing chm-acteristics. A new gas sensor has been fabricated by incorporating the different multilayer LB fihns into the gate electrode of a MOSFET, fomling ml mray of charge flow trmlsistor (CloT). On the application of a gate voltage (VGs), greater tlaml the threshold voltage (VTI0, a delay is observed in the response oftbe drain cun-ent, it is due to the time taken for the resistive gas sensing fihn to charge up to VGs. This delay characteristic has been fomld to depend on the concentrations of NO2, suggesting tlaat the Clot device cml be used as ml effective gas sensor. Resolts are presented of studies the dc operating mid mm on chm-acteristics as well as gas sensing property, showing tlaat the device can detect reversibly concentration of NO2 gas down to 5 ppm at room temperature.