Abstract
Determining the refractive index (n) and extinction coefficient (k) of materials is of core importance in optoelectronic and photonic devices. This study demonstrates a simple yet novel method to determine n and k of unusual encapsulant materials for back contact photovoltaic (PV) modules. To avoid the problem of encapsulant browning, two non-traditional encapsulant materials, i.e., polybutadiene ionomer and thermoplastic polyolefin, are utilized as an alternative to traditionally used ethylene vinyl acetate (EVA). The n and k samples were calculated by solving the optical parameters using MATLAB code which requires transmittance and reflectance values from spectrophotometer. To validate our proposed method, glass and EVA are used as a reference. The computation of refractive index of glass and EVA has achieved an accuracy of +/- 0.007 and +/- 0.006, respectively. Whereas computation of extinction coefficient of glass and EVA has achieved an accuracy of +/- 2.37 x 10(-6) and +/- 4.69 x 10(-6), respectively. Thus, calculated results of n and k for glass and EVA are found in good agreement as compared to the standard values, whereas the marginal difference is within acceptable experimental error. This method can serve as a tool to find n and k of non-standard materials prior to their deployment in PV modules.