Laser-grooved backside contact solar cells with 680-mV open-circuit voltage

In this paper, we demonstrate for the first time the use of the laser-grooved solar cell technology, a proved commercial technology, for the implementation of the rear junction backside contact solar cells. Laser-grooved backside contact solar cells, designated as interdigitated backside buried contact (IBBC) solar cells, have been fabricated on planar, n-type, 1 Ω·cm wafers with a single layer SiO₂ anti-reflection coating, achieving 17% efficiency with open-circuit voltage (V_oc) of more than 680 mV. Front and rear surface recombination velocities of 350 cm/s and 4800 cm/s, and more than 1 ms of post-processing bulk lifetime confirm that commercial laser-grooved solar cell fabrication process is capable of obtaining the efficiency advantages of the rear junction, backside contact design. Moreover, this paper presents a side-by-side comparison between the more conventional double-sided buried contact solar cell and the IBBC solar cell. The advantages of higher short-circuit current in the latter design due to no contact shading loss, and higher V_oc due to inherently lower surface recombination velocity of the IBBC structure are demonstrated.