Enhanced performance of solar cell with n+ emitter by SiO2 nanospheres assisted liquid phosphorus diffusion.

• SiO 2 nanospheres were used for more uniform phosphorus diffusion. • An enhancement of minority carrier lifetime from 42 μs to 56 μs was obtained. • A small square resistance of 22 Ω/sq was made at high phosphoric acid concentration. • The efficiency in the cell center was enhanced by 40.54% using the nanospheres. In order to improve the quality of n+ emitter fabricated by phosphorus doping, SiO 2 nanospheres were added into a phosphoric acid solution for spin-on doping. Through a complete analysis of the trade-off between the diffusion uniformity and sheet resistance, the particle size of SiO 2 nanospheres is selected to be 230 nm. It is found that with the increase of phosphoric acid concentration from 50% to 85%, the average sheet resistance decreases from 128.5 Ω/sq to 18.1 Ω/sq, and the diffusion uniformity increased from 95.2% to 98.5%. In a large concentration range, the surface doping concentration of the emitter will increase with phosphoric acid, but when the concentration of phosphoric acid reaches 80%, the surface doping concentration will be almost unchanged. Nevertheless, different from above, the p-n junction depth has little dependence on the phosphoric acid concentration. Moreover, the efficiencies in the solar cell center and edge are enhanced by 40.54% and 88.08% respectively using SiO 2 nanospheres assisted diffusion. [ABSTRACT FROM AUTHOR]