Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, CAS
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Fig. 1 Light management in all-perovskite tandem solar cells
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Fig. 1 Light management in all-perovskite tandem solar cells
Credit: Hairen Tan et al.
Introduction
The development of clean and low-cost solar photovoltaic technology is crucial for the global transition toward carbon neutrality and sustainable energy. Monolithic all-perovskite tandem solar cells, constructed by stacking wide- and narrow-bandgap perovskite sub-cells with an intermediate interconnecting layer, offer a theoretical efficiency of up to 45%, positioning them as a promising next-generation photovoltaic technology. However, the short-circuit current density (Jsc) of state-of-the-art all-perovskite tandem devices remains limited to below 16.7 mA cm-2, primarily due to insufficient light utilization, which hinders further progress. Recently, Assistant Professor Renxing Lin and Professor Hairen Tan from the College of Engineering and Applied Sciences, Nanjing University published a comprehensive review titled “Light Management in Monolithic All-Perovskite Tandem Solar Cells” in Light: Science & Applications. This review describes the particularity of light management in all-perovskite tandem solar cells, and summarizes their advances, challenges, and prospects (Fig. 1).
Special light management in all-perovskite tandem solar cells
Light management significantly influences the photocurrent generation in all-perovskite tandem cells. Before photons reach the perovskite absorber layers, optical losses occur due to interfacial reflection and parasitic absorption within the functional layers. Additionally, optical losses within the absorber arise not only from insufficient photon absorption but also from parasitic carrier transport. This review systematically categorizes light management strategies into two approaches based on the photon pathway (Fig. 2): first, minimizing external optical losses to maximize the number of photons entering the absorber; and second, enhancing the photon capture capability of the absorber to improve photon-to-carrier conversion efficiency, thereby generating more electron-hole pairs.
Notably, single-junction perovskite cells can achieve high Jsc values simply by reducing parasitic absorption in non-active layers and increasing the thickness of the active layer. In contrast, the optical design of all-perovskite tandem cells is more complex for three main reasons (Fig. 2). First, the multi-layer structure and the introduction of an interconnecting layer between the two sub-cells not only increase optical losses but also require careful consideration of spectral distribution and current matching between the sub-cells. Second, the narrow-bandgap lead-tin mixed perovskite inherently exhibits high defect density and low absorption coefficients in the infrared region, making it challenging for the tandem device to capture near-infrared photons effectively. Third, thin-film interference effects pose new challenges for optimal current matching in the bottom narrow-bandgap sub-cell. These factors collectively introduce critical trade-offs not present in single-junction devices, meaning that all-perovskite tandem cells require more targeted light management strategies.
The core — Current matching principle of all-perovskite tandem solar cells
In tandem solar cells, light management strategies differ fundamentally from those in single-junction devices, owing to combined effects of current matching, independent sub-cell, and complex multilayer interference. For all-perovskite tandem configurations, optical optimization of the narrow-bandgap sub-cell, compared with the wide-bandgap sub-cell which already approaches its optical limit, proves more cost-effective. However, enhancing only the narrow-bandgap sub-cell may disrupt the original current balance, leading to overall device degradation. Reaching a new current-matched state requires co-optimization of both sub-cells—including their bandgaps and thicknesses (Fig. 3). As the narrow-bandgap sub-cell is optically improved, the wide-bandgap sub-cell generally evolves toward a narrower bandgap and greater thickness to restore current matching and enhance overall performance.
Reducing optical losses — Maximization of photon incidence
Despite precise bandgap matching and thickness optimization enabling rational spectral allocation between sub-cells, a significant portion of incident photons still fail to reach the perovskite absorber layers, constituting a key factor limiting the photocurrent in all-perovskite tandem cells. The lost photons due to interfacial reflection and parasitic absorption before entering the absorbers are categorized as external optical losses. This review identifies that such losses primarily originate from reflection and parasitic absorption (Fig. 4). The total reflection of all-perovskite tandem cells exhibits distinct spectral dependence: ultraviolet losses arise mainly from intrinsic glass reflection; visible-range losses are dominated by cumulative reflection at multiple interfaces such as glass/ITO and perovskite/transport layers; in the near-infrared region, interface reflection is compounded by the inherently weak absorption of narrow-bandgap perovskite. Parasitic absorption predominantly occurs in optically non-ideal functional layers, including the front ITO electrode, metal recombination Au layer, PEDOT: PSS, and the back Cu electrode. Apart from inevitable metal electrode losses caused by surface plasmon resonance, remaining optical losses can be classified into reflection losses and parasitic absorption from the front electrode, transport layers, and interconnecting layer.
Improving light utilization — Maximization of photon conversion
Beyond reducing optical losses, enhancing photon utilization is equally critical in all-perovskite tandem solar cells. While the former aims to increase incident photons, the latter focuses on effective charge generation and collection to maximize internal exploitation of these photons. Implementing efficient light utilization strategies enables monolithic all-perovskite tandems to minimize photon escape and leverage incoming photons more effectively. In line with the structure characteristics of all-perovskite tandem cells, we outline several light management approaches for improved photon utilization: optimizing narrow-bandgap perovskite films for enhanced low-energy photon harvesting, integrating micro-/nano- structures to extend photon path length, designing more junction architectures to reduce high-energy photon loss, and engineering bifacial configurations to capture ambient illumination (Fig. 5).
Conclusions and outlook
In summary, all-perovskite tandem solar cells have achieved remarkable progress within a relatively short time, outperforming single-junction perovskite devices and other tandem architectures. Innovative optical designs and light-management strategies are poised to play a crucial role in their further development. Guided by current-matching principles, this review systematically devises tailored light-management approaches aimed at reducing optical loss and enhancing photon utilization. Furthermore, it outlines future directions and feasible strategies from perspectives of fundamental concepts, materials, structures, and realistic spectral conditions—spanning spectral modification, colored tandem devices, and modules (Fig. 6). We remain optimistic regarding the potential of perovskite-based technologies for efficiency breakthroughs, scalable production, and broad application. Continued research and development are expected to drive substantial advancements, positioning all-perovskite tandem cells as a promising competitor in the photovoltaics landscape.
Light Science & Applications
10.1038/s41377-025-02120-5
Light management in monolithic all-perovskite tandem solar cells
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Media Contact
WEI ZHAO
Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, CAS
zhaowei@lightpublishing.cn
Light Publishing Center, Changchun Institute of Optics, Fine Mechanics And Physics, CAS
Copyright © 2026 by the American Association for the Advancement of Science (AAAS)
Copyright © 2026 by the American Association for the Advancement of Science (AAAS)
