Optical design of multi-stacked intermediate layers with wavelength-selective reflectance for a-Si:H/μc-Si:H tandem solar cells

The optical study of multi-stacked intermediate layers in an a-Si:H/μc-Si:H tandem solar cell using simulator called Optical was performed. We have theoretically investigated the effect of refractive index and thickness on light reflectance spectrum at the n-top layer/intermediate layer interface. It was found that the triple or four intermediate layers whose high reflectance at a short wavelength and low reflectance at a long wavelength are applicable to a- Si:H/μc-Si:H tandem solar cells. To verify the numerical results, single and triple layers were fabricated, and their transmittance spectra were measured. Also, the experimental results show that a triple intermediate layer is beneficial as a reflector layer for tandem solar cells. However, optimization of a thickness combination is urgently required especially in multi-stacked intermediate layers.