Monolithic perovskite/silicon tandem solar cells enabled by multifunctional TiOx interconnects

Journal article

Perovskite-on-silicon tandem solar cells have emerged as a leading technology enabling high power conversion efficiencies (PCE) over 30%. Despite current progress, the intrinsic multilayer device design presents vast challenges in complexity, which can be a drawback in future mass production. Multifunctional nanolayer materials that simplify large-scale production are therefore highly desirable. Herein, a $TiO_x$ layer ($\sim$3--5 nm) grown by atomic layer deposition (ALD) enables a series interconnection of a perovskite $n$-$i$-$p$ top cell with a silicon wafer directly. The $TiO_x$ layer serves as an all-in-one interconnect, fulfilling the functions of silicon surface passivation, hole extraction from silicon, and recombination junction at the top/bottom cell interface. As a result, a proof-of-concept 22.4%-efficient tandem device is demonstrated. Furthermore, an improved PCE of 26.5% is achieved by capping the $TiO_x$ with a thin ALD-$TiN_y$ layer ($\sim$4 nm). This represents a performance as high as the reference tandem device (PCE = 25.5%) that uses amorphous silicon passivating selective contacts and an indium-tin-oxide interlayer. Such a $TiO_x$ multifunctional nanolayer can reduce the number of deposition tools and eliminate the need of an indium-based interconnection. It offers a potential for low-cost, scalable, and sustainable tandem solar cell manufacturing.

Authors: Matsui, T; McDonald, C; Mirzehmet, A; McQueen, J; Bonilla, RS

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Wiley
• Journal: Small
• Volume: 21
• Issue: 24
• Article number: 2500969
• Publication date: 2025-04-27
• Acceptance date: 2026-03-31
• DOI: 10.1002/smll.202500969
• EISSN: 1613-6829
• ISSN: 1613-6810
• Language: English
• Keywords: perovskite/silicon tandem solar cell; passivating contact; titanium oxide; titanium nitride; recombination junction