On the removal behavior of aluminum paste for silicon solar cell

Abstract

The removal behavior of the aluminum paste was investigated using thermogravimetric analyzer, and it was found that the mass loss curve could be divided into two main stages including low-temperature and high-temperature stages and a complex transition between them. The pre-exponential factors of the two main stages were calculated by Kissinger method. And the activation energies were determined using different methods named as Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sinose (KAS) and Kissinger. The dependence of the activation energy on the conversion has been analyzed in detail. The activation energy of the low-temperature stage keeps approximately constant, and the average value is 38.74 kJ mol−1 of FWO method and 33.86 kJ mol−1 of KAS method. According to KAS method, the activation energy for the high-temperature stage decreases from 157.03 to 94.65 kJ mol−1 with the temperature increasing from 596 to 675 K. The variation range of the activation energies indicates the existence of a complicated reaction mechanism during the high-temperature stage. Though high removal rate during the low-temperature stage is beneficial to reducing the processing time of silicon solar cells, the heating rate should be controlled when the temperature is close to the value resulting in the maximum mass loss rate to avoid causing defects in the aluminum back electrode.