Optical Coupling Efficiency, Photon Loss, and Efficiency Estimates for c-Si PERC Modules Enhanced with Downconverting Films and Nanocomposites

Downconversion is an attractive process to enhance the performance of photovoltaic devices, enhancing conversion efficiency by both increasing photon flux into the active layers and improving the spectral response. The achievable efficiency enhancement, however, depends on the coupling efficiency between the downconverting material and the solar cell and on the placement and method of incorporation into the photovoltaic module. This study uses a combination of wave and geometrical optics to model the coupling efficiency and resulting photovoltaic performance for three configurations of Si photovoltaic modules containing downconverters. We find that the optical coupling is greater than 80% when the downconverting film is incorporated at the textured SiNx/Si interface or when the downconverters are dispersed within the encapsulant to form a composite. However, the optical coupling does not exceed 30% when the downconverting film is placed between the encapsulant and the cover glass because of increased internal reflection and trapped modes. The efficiency estimates show that placing the downconverting film on the SiNx/Si pyramids yields the greatest increase in power conversion efficiency compared to the reference device, approximately 2% absolute, and the efficiency enhancement is primarily due to photon multiplication rather than spectral shifting.

University of Minnesota (UMN), BlueDot Photonics

John Keil and Jared S. Silvia and Daniel M. Kroupa and Vivian E. Ferry

ACS Applied Energy Materials

downconversion,light management,optical coupling,optical loss,photovoltaics

2023

11

10.1021/ACSAEM.3C01792/SUPPL_FILE/AE3C01792_SI_001.PDF

25740962

21

10978-10986

American Chemical Society

6