Closing the gap between n‐ and p‐type silicon heterojunction solar cells: 24.47% efficiency on lightly doped Ga wafers

Abstract

Silicon heterojunction (SHJ) solar cells can be formed using n‐type or p‐type silicon wafers. To foster the increasing industrial interest of SHJ, cheaper p‐type wafers with a good availability might be preferred, but until today, they yield lower cell efficiency compared with n‐type and show instabilities in the particular case of boron doping. This work shows that the production flow of high performance rear‐junction bifacial n‐type cells can be applied to front‐junction p‐type cells without process alterations and with a loss of efficiency as low as −0.3%abs provided that the wafer bulk lifetime is high enough. For this, we propose the use of wafers with gallium doping on which we obtained on a semi‐industrial pilot line SHJ p‐type cells mostly stable under moderated heat and light and with an efficiency closed to n‐type references. The best p‐type cell was externally certified at 24.47% total area.

Investigation of p-Type Silicon Heterojunction Radiation Hardness

“…While LEO orbits are rather proton rich, we choose electrons beams as a first step here, for there high penetration depth creating uniform defects throughout the various Si thicknesses considered here. Amorphous/Crystalline Si heterojunction solar cells were manufactured on the industrial pilot line of CEA [11], with state-of-the-art gallium-doped Si wafers. Exsitu Begin-Of-Life (BOL) and End-Of-Life (EOL) current voltage and external quantum efficiency characterizations were used to quantify the degradation linked to electrons irradiation.…”