title: Exceptionally omnidirectional broadband light harvesting scheme for multi-junction concentrator solar cells achieved via ZnO nanoneedles.
abstract: GaInP/GaAs/Ge triple-junction concentrator solar cells with significant efficiency enhancement were demonstrated with antireflective ZnO nanoneedles. The novel nanostructure was attained with a Zn(NO3)2-based solution containing vitamin C. Under one sun AM 1.5G solar spectrum, conversion efficiency of the triple-junction device was improved by 23.7% via broadband improvement in short-circuit currents of 3 sub-cells after the coverage by the nanoneedles with a graded refractive index profile. The efficiency enhancement further went up to 45.8% at 100 suns. The performance boost through the nanoneedles also became increasingly pronounced in the conditions of high incident angles and the cloudy weather, e.g. 220.0% of efficiency enhancement was observed at the incident angle of 60°. These results were attributed to the exceptional broadband omnidirectionality of the antireflective nanoneedles.
authors.affiliation: Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, King Abdullah University of Science &Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.|Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC.
authors.forename: Li-Ko
authors.initials: LK
authors.lastname: Yeh
authors.affiliation: Graduate Institute of Electronics Engineering, National Taiwan University, Taipei 10617, Taiwan, ROC.
authors.forename: Wei-Cheng
authors.initials: WC
authors.lastname: Tian
authors.affiliation: Department of Optics and Photonics, National Central University, Chung-Li 32001, Taiwan, ROC.
authors.forename: Kun-Yu
authors.initials: KY
authors.lastname: Lai
authors.affiliation: Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, King Abdullah University of Science &Technology (KAUST), Thuwal 23955-6900, Saudi Arabia.
authors.forename: Jr-Hau
authors.initials: JH
authors.lastname: He