Broadband-sensitive Ni2+–Er3+ based upconverters for crystalline silicon solar cells. Issue 60 (9th June 2016)

• Record Type: Journal Article
• Authors: Luitel, Hom N.; Mizuno, Shintaro; Tani, Toshihiko; Takeda, Yasuhiko
• Is Part Of: RSC advances. Volume 6:Issue 60(2016)
• Page Start: 55499
• Page End: 55506
• Publication Date: 2016-06-09
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra10713c
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The newly developed CaZrO3 :Er 3+, Ni 2+ broadband-sensitive upconverter utilizes 1060–1600 nm solar irradiation and can surpass the limiting efficiency of c-Si solar cells. Abstract : We have developed Ni 2+, Er 3+ codoped CaZrO3 broadband-sensitive upconverters that significantly broaden the sensitive range, and hence overcome the shortcomings of conventional Er 3+ doped upconverters used for crystalline silicon (c-Si) solar cells that utilize only a small fraction of the solar spectrum around 1550 nm. We have designed the combination of sensitizers and host material to utilize photons that are not absorbed by c-Si itself or Er 3+ ions. Six coordinated Ni 2+ ions substituted at the Zr 4+ sites absorb (1060–1450) nm photons and transfer the energies to the Er 3+ ions, and the Er 3+ upconverts at 980 nm. Co-doping with monovalent charge compensators such as Li + for high Er 3+ solubilisation at the Ca 2+ sites and multivalent ions (Nb 5+ ) for stabilization of Ni 2+ at the Zr 4+ sites is essential. In addition to 1450–1600 nm (≈2 × 10 20 m −2 s −1 ) photons directly absorbed by the Er 3+ ions, we have demonstrated upconversion of 1060–1450 nm (≈6 × 10 20 m −2 s −1 ) photons in the Ni 2+ absorption band to 980 nm photons using the CaZrO3 :Ni 2+, Er 3+ upconverters. Compared with the current density gain of present c-Si solar cells (∼40 mA cm −2 ), the upconverted photons could increase this by ∼7.3 mA cm −2, which is about 18% improvement. This architecture for broadband-sensitive upconversion may pave a new direction for the improvement in efficiency of the present c-Si solar cells to surpass the limiting conversion efficiency of single-junction solar cells.