Screen-Printable Conductor Metallizations for Industrial n-TOPCon Crystalline Silicon Solar Cells

Optimally prepared industrial n-type TOPCon c-Si bifacial solar cells (156 mm × 156 mm) fabricated with cost-effective screen-printable front-side and rear-side metallization pastes had a median solar cell efficiency of 22.19 ± 0.10% and bifaciality Eff factor of 82.3%. A front-side paste comprising silver, metallic aluminum, and inorganic frit was designed to contact p
⁺
boron-diffused Si emitter surfaces with SiN
x
: H-Al
2
O
3
antireflection-passivation layers. A rear-side paste comprising silver and inorganic frit was designed to contact n
⁺
phosphorous-diffused Si surfaces with tunnel-SiO
x
/n
⁺
poly-Si/SiN
x
: H layers. Solar cell electrical data suggests efficiency is being limited primarily by the front-side metallization paste. The final front-side metallization microstructure shows isolated metallic aluminum particles surrounded by solidified glass within the bulk sintered silver conductor line. The front-side conductor metal-p
⁺
boron-diffused Si emitter contact region shows continuous interfacial films decorated with silver colloids located between the bulk conductor metal and Si emitter surface. A microstructural model suggests electrical contact for the front-side contact region occurs by a tunneling mechanism though the residual interfacial films.