Abstract
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.
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In the power generation sector, the market share of crystalline silicon (c-Si) photovoltaic (PV) technology has expanded rapidly in recent times with continuously improving cell efficiencies along with reduced multigigawatt-scale manufacturing costs. However, the performance of the mainstream c-Si PV technologies in production is largely constrained by power losses in the metal-silicon-contacted regions. As an alternative, the industry is moving toward integrating passivating contacts in device architectures, which will allow approaching single-junction cell efficiencies beyond 26%. Most notably, passivating contact (PC) schemes based on polycrystalline silicon junctions and hydrogenated amorphous silicon stacks have particularly attracted attention for industrial adoption in the near future. This perspective focuses on the latter PC technology, more commonly known as silicon heterojunction (SHJ) technology, which achieved the highest power conversion efficiency to date for a single-junction c-Si solar cell. Moreover, the SHJ technology has been utilized in realizing world record perovskite/c-Si tandem solar cells. Therefore, techno-economic barriers for the industrial adoption of SHJ technology are discussed herein.
Crystalline silicon heterojunction photovoltaic technology was conceived in the early 1990s. Despite establishing the world record power conversion efficiency for crystalline silicon solar cells and being in production for more than two decades, its present market share is still surprisingly low at approximately 2%, thus implying that there are still outstanding techno-economic challenges that are preventing silicon heterojunction solar cells from becoming the mainstream photovoltaic technology. Here, we revisit these techno-economic challenges and discuss potential solutions for overcoming them.