Application of luminescence technology for solar PV industry

The luminescence technology is a non-destructive testing and can be applied for kinds of solar cells such as c-Si, thin film (α-Si, CIGS, and CdTe) and multi-junction solar cells. The luminescence intensity is correlated to the quality of absorber or junction and suitable to be developed as monitors of device property during process. Photoluminescence (PL) and Electroluminescence (EL) are most common luminescence metrologies and they can help to identify the band gap, defect level, defect density, radiative recombination coefficient, junction quality, and implied open circuit voltage (Voc). The 2D PL/EL image can help to evaluate the uniformity and physical defect information such as crack, contact disconnection, shunting points, serious resistance distribution, and impurity. The failure analysis of long-term reliability test (light illumination and thermal stress) by the combination of PL/EL technology can help to identify the key root cause. The qualitative analysis of PL/EL metrologies can apply for process correlation to stabilize the production line and/or further improve the efficiency.