Independent Al2O3/SiNx:H and SiO2/SiN x:H Passivation of p+ and n+ Silicon Surfaces for High-Performance Interdigitated Back Contact Solar Cells

In order to improve interdigitated back contact (IBC) solar cell efficiencies, the entire solar cell surface must be well passivated. Al
₂
O
₃
/SiN
_x
:H and SiO
₂
/SiN
_x
:H passivation stacks have been widely adopted for high-efficiency silicon solar cells. We explored IBC solar cells with 1) only SiO
₂
/SiN
_x
:H; 2) only Al
₂
O
₃
/SiN
_x
:H passivating both diffused surfaces; or 3) independent p
⁺
emitter and n
⁺
back surface field (BSF) passivation with Al
₂
O
₃
/SiN
_x
:H and SiO
₂
/SiN
_x
:H respectively. First, stacks were optimized through simulation (using a device model in 3D Quokka) by varying the recombination parameter Jo. Second, solar cells were fabricated with a low-cost high-throughput screen-printing technique. Third, simulated J
_sc
, V
_oc
, F F , and η values closely matched the experimental results for passivation schemes 1 and 2. Passivation scheme 3 could not be realized experimentally due to fabrication difficulties, while its simulated values were 688 mV, 41.4 mA/cm
²
, 80.8%, and 23.0%, respectively. It is clear that independent passivation captures material advantages for each diffused region for enhanced solar cell performance compared with conventional passivation of both diffused regions with a single passivation stack.