Design Of A Light Heating And Infrared Temperature Measurement System For The Substrate During Spin-coating

Spin-coating has become an important step in the preparation process of organicthin film photovoltaic device, which can affect the microstructure of thin film.Spin-coating has advantages of simple process, low cost and high-quality thin filmperformance. These factors including the rotational speed of spin coater, thespin-coating time and the disturbance of ambient gas on the film will affect the filmquality and morphology, thereby affecting the photoelectric conversion efficiency ofthe device. In addition, the film quality and morphology may relate to the temperatureof substrate, for spin-coating at room temperature generally, but the processedsolution temperature differs from room temperature, when the solution is dropped onthe substrate, the temperature difference may lead to the internal structure of solutionchanged uncertainly. Meanwhile，this change affects the film quality and morphology.For example, in the preparation of organic thin film solar cell, when spin-coating thesubstrate is at room temperature. There is no report on whether adjusting the substratetemperature would obtain a better quality film and improve the device performance.Based on this consideration, a light heating and temperature measurement system forspin-coating is designed.Firstly, through researching spin coaters on the market, such as the SCx series ofHuidexin Inc. in Beijing, the MSC-650-xN Series of Macro Inc. in Hongkong, theKW-4A and KW-4A-x series of Chemat Inc. in America, none of them has thefunction of heating the substrate.Secondly, without destroying the original structure of spin coater, a non-contacttemperature measurement and heating device is designed. The device consists of fiveparts including control module, temperature measurement module, heating module,input module and display module. The control module uses STC12C5A60S2microcontroller, the temperature measurement module uses MLX90614ACF infraredthermometer and the heating module uses AC220v/1000W infrared halogen lampswith a trapezoidal cylinder shade. The simulation result of heating lamps with LightTools5.1shows that the condenser and uniformity of the lamps are preferableand the irradiance reaches1W/cm~2. PID (Proportion Integration Differentiation)temperature control is used, and the PID parameters are optimized by SIMULINKtoolbox in MATLAB7.1.Finally, this device has be tested during the preparation process of organic thinfilm solar cell showing that the ITO glass substrate can be heated from roomtemperature to120℃within5minutes, and the absolute error of temperature doesnot exceed1.5℃, which can satisfy the needs of preparing organic thin filmphotovoltaic device.