Bandgap grading and Al0.3Ga0.7As heterojunction emitter for highly efficient GaAs-based solar cells

• Published in: Solar energy materials and solar cells 2016-10, Vol.155, p.264-272
• Main Authors: Hwang, Sun-Tae, Kim, Soohyun, Cheun, Hyeunseok, Lee, Hyun, Lee, Byungho, Hwang, Taehyun, Lee, Sangheon, Yoon, Wonki, Lee, Heon-Min, Park, Byungwoo
• Format: Article
• Language: English
• Subjects: Bandgap grading; GaAs solar cells; Heterojunction
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2016.06.009

Both an Al0.3Ga0.7As heterojunction in the p-type emitter and a bandgap-graded layer in the n-type light absorbing base were employed in the GaAs-based solar cells. The simulation by AFORS-HET (Helmholtz-Zentrum Berlin) confirmed that the Al0.3Ga0.7As heterojunction enhanced the open-circuit voltage (Voc) by ~2%, and the n-type bandgap grading increased the fill factor by ~1%, respectively. The increased power conversion efficiency by ~3% supported the simulation results. An additional efficiency gain was obtained by the shape optimization of the band bending in the 80-nm compositional profile, increasing Voc up to 1.103V. The cell with the anti-reflective coating exhibited high performance with a power conversion efficiency of 28.7% under 1sun illumination, close to the world record of 28.8%. [Display omitted] •Al0.3Ga0.7As heterojunction in the p-type emitter improved the Voc of the GaAs solar cells.•Bandgap-graded layer in the n-type base increased the FF and the conversion efficiency.•Thickness and shape optimization of bandgap-graded layer further enhanced the efficiency.•28.7% conversion efficiency at 1sun illumination was achieved, close to the world record.