The ever-increasing electricity demand from renewables has stimulated growth in the photovoltaic
(PV) industry. Yet, while grid parity has already been achieved in several countries, a continued decline in module prices coupled with further efficiency improvements at an annual growth rate of ∼0.5%abs are needed to sustain its market growth. Mainstream PV technologies
are still based on crystalline silicon
(c-Si) wafers with heavily doped regions and directly metallized contacts. However, these cause band-gap narrowing, Auger recombination losses
, and contact recombination losses. Passivating contact (PC) technologies can overcome these limitations by decoupling surface passivation
and contact formation requirements. Among PC technologies, amorphous silicon-based silicon heterojunction
(SHJ) solar cells have established the world record power conversion efficiency
for single-junction c-Si PV. Due to their excellent performance and simple design, they are also the preferred bottom cell technology for perovskite/silicon tandems. Nevertheless, SHJ technology accounts for only ∼2% of the current PV market share. In this review, we discuss the techno-economic challenges for large-volume SHJ manufacturing. In doing so, we highlight critical areas that need to be addressed for enabling terawatt-scale SHJ deployment.