Photon management effects of hybrid nanostructures/microstructures for organic-silicon heterojunction solar cells

Photon management and carrier separation play crucial roles on designing highly efficient organic-silicon heterojunction solar cells. Aiming at suppressing optical reflection loss and improving carrier separation efficiency simultaneously, in this paper, we experimentally fabricated hybrid nanostructured/microstructured surfaces by combining the advantages of microstructures and nanostructures. The hybrid nanostructured/microstructured surfaces were prepared by stacking nanoholes on the micropyramids via using a cost-effective method. In terms of the optical properties, the light reflection, angle-dependent light absorption, and polarization-dependent light absorption of the different structured surfaces were investigated. The results indicated that the hybrid nanostructures/microstructures exhibited ultralow reflection in the broadband wavelength range of 300 to 1100 nm (average reflection is 1.8%). Meanwhile, the hybrid nanostructured/microstructured surfaces possessed superior omnidirectional and polarization-independent properties compared to the unitary structures such as pyramid and nanohole. Furthermore, these different structured surfaces were simply used to fabricate the PEDOT:PSS/n-Si heterojunction solar cells to show the electrical properties. It was found that the PEDOT:PSS/hybrid Si solar cells showed a PCE of 9.96%, which was greater than the PEDOT:PSS/pyramid Si and PEDOT:PSS/black Si solar cells, owing to the compromise among light absorption, junction area, and minority carrier lifetime. The present work will provide a promising way to fabricate high-performance and low-cost PEDOT:PSS/n-Si heterojunction solar cells by using hybrid nanostructured/microstructured surfaces.