Increasing efficiency of hierarchical nanostructured heterojunction solar cells to 16.3% via controlling interface recombination†
Silicon nanostructures show great promise for use in photovoltaic applications, owing to their enhanced light-harvesting characteristics, which allow them to form radial p–n junctions for effectively generating/separating photoexcited carriers. They are also low-cost materials and thus suitable for producing solar cells. In this study, hierarchical Si structures consisting of microscale pyramids and nanoscale pillars were fabricated through wet anisotropic texturing and reactive ion etching. Further, these substrates, which had a core–shell structure, were used to fabricate radial heterojunction Si solar cells through interface engineering with tetramethylammonium hydroxide. The substrates were pretreated with a hydrogen plasma and subsequently subjected to amorphous Si thin-film passivation. This resulted in solar cells with a markedly higher broadband wavelength; however, the electrical properties of the cells almost remained unaffected. Further, the heterojunction solar cells, which had a hierarchical nanostructure and were fabricated using as-cut Czochralski n-type Si substrates, exhibited an efficiency of 16.3%, which is the highest ever reported for such cells.