An innovative design for a monolithic perovskite/silicon tandem solar cell, featuring a mesoscopic perovskite top subcell and a high-temperature tolerant homojunction c-Si bottom subcell.

The tandem cell structure is the most promising solution for the next generation photovoltaic technology to overcome the single‐junction Shockley–Queisser limit. The fabrication of a perovskite/c‐Si monolithic tandem device has not yet been demonstrated on a c‐Si bottom cell produced from an industrial production line. Here, a c‐Si cell with a tunneling oxide passivating contact (TOPCon) structure produced on a production line as the bottom cell of a tandem device, and a top cell featuring solution‐processed perovskite films to form the tandem device are used. The c‐Si cell features a rough damage etched, but untextured front surface from the wafering processes. To combat the challenge of rough surfaces, several strategies to avoid shunt paths across carrier transport layers, absorber layers, and their interfaces are implemented. Moreover, the origin of reflection loss on this planar structure is investigated and the reflection loss is managed to below 4 mA cm−2. In addition, the source of the voltage loss from the TOPCon bottom cell is identified and the device structure is redesigned to be suitable for tandem applications while still using mass production feasible fabrication methods. Overall, 27.6% efficiency is achieved for a monolithic perovskite/c‐Si tandem device, with significant potential for future improvements.

Thin SiO x interlayers are often formed naturally during the deposition of transition metal oxides on silicon surfaces due to interfacial reaction. The SiO x layer, often only several atomic layers thick, becomes the interface between the Si and deposited metal oxide and can therefore influence the electrical properties and thermal stability of the deposited stack. This work explores the potential benefits of controlling the properties of the SiO x interlayer by the introduction of pregrown high-quality SiO x which also inhibits the formation of low-quality SiO x from the metal-oxide deposition process. This work demonstrates that a high-quality pregrown SiO x can reduce the interfacial reaction and results in a more stoichiometric MoO x with improved surface passivation and thermal stability linked to its lower D it. Detailed experimental data on carrier selectivity, carrier transport efficiency, annealing stability up to 250 °C, and in-depth material analysis are presented.

grain (Note S1, Supporting Information), which indicated that those new perovskite phases likely contained 4M-PEACl. We noted that no Cl signal was detected at the grain interior of the perovskite films according to the EDS results. Although this

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