Laser textured heterojunction solar cells on 45 um thick Si wafers: Effect of optical configuration and light trapping

The fabrication and performance of heterojunction Si solar cells on ~ 45 μm thick Si wafers with laser textured surfaces at the front or back, and with Al or ITO/Ag back reflectors is presented. Devices with a front junction and rear lasing are compared to those with front lasing and rear junction. V_oc=700 mV and J_sc=35 mA/cm² are obtained on cells with rear laser texture verifying that very good passivation and light trapping was obtained. FF ranged from 60 to 79% depending on the back contact processing. Devices with front heterojunction, rear laser texture and ITO/Ag back reflector achieved >17.5% efficiency with an optimized defect etch. Reducing defects at the lased surface is crucial to obtain high V_oc and J_sc.