Light Management in All-Perovskite Tandem Solar Cells

By Dr. Noopur JainReviewed by Louis CastelMar 18 2026

Why Light Utilization Limits Tandem Solar Cell Performance
Optical Design Strategies and Modeling Approaches
Coupled Optical–Electrical Design Challenges
The Path Forward for Perovskite Tandem Photovoltaics
Journal Reference

In a recent review article published in the journal Light Science & Applications, researchers addressed the critical role of light management in advancing monolithic all-perovskite tandem solar cells (APTSCs), which have emerged as a promising technology to surpass the efficiency limits of single-junction solar cells.

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Why Light Utilization Limits Tandem Solar Cell Performance

APTSCs combine wide-bandgap (WBG, approximately 1.8 eV) and narrow-bandgap (NBG, approximately 1.2 eV) perovskite materials in tandem configurations to utilize a broader spectrum of sunlight, leading to improved power conversion efficiencies (PCE).

While recent APTSCs have achieved impressive PCEs, such as a two-terminal (2T) device reaching 30.1% with an open-circuit voltage of 2.20 volts, short-circuit current density of 16.7 mA/cm², and fill factor of 81.8%, these current densities are still below theoretical expectations of around 18 mA/cm².

The primary bottleneck is the suboptimal utilization of incident light, which results from substantial optical losses, including reflection at various interfaces and parasitic absorption within non-active layers. These losses limit the generation of photocurrent and, consequently, the overall device efficiency.

The review highlights the need for specialized light management techniques tailored to the multilayer structure and specific challenges of APTSCs to minimize losses and enhance photon-to-carrier conversion, particularly by reducing external optical losses and improving internal photon utilization.

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Optical Design Strategies and Modeling Approaches

The review provides a comprehensive summary of recent advancements and strategies in optical design and light management for APTSCs.

It examines the modeling approaches used to understand and optimize light interactions within tandem structures, including ray tracing, transfer matrix methods (TMM), finite-difference time-domain (FDTD), finite element methods (FEM), and rigorous coupled-wave analysis (RCWA). These tools enable the prediction of current matching, guide the design of layer thicknesses and bandgaps, and support the analysis of complex nanophotonic structures tailored for APTSCs. For example, TMM is widely used for thickness and spectral optimization but is inherently limited to one-dimensional models, whereas FDTD and RCWA are better suited for analyzing two- and three-dimensional nanostructured surfaces that enhance light trapping.

The article also details the types of optical losses encountered in APTSCs, quantifying the limits imposed by absorption in functional layers and interfacial reflections. It further assesses how the thickness and bandgap of WBG perovskites influence the achievable short-circuit current density. To address these challenges, strategies such as employing low-optical-loss interconnecting layers, optimizing transparent electrodes, and introducing advanced nanophotonic textures are discussed to reduce parasitic losses and improve light-harvesting efficiency.

Additionally, the review emphasizes that light management in APTSCs differs significantly from that in single-junction cells. The tandem architecture requires strict current matching and involves complex interference effects, making optical design a multi-variable optimization problem. Experimental developments highlighted include improvements in grain surface passivation for NBG perovskites to reduce defect densities and enhance charge transport, enabling better-performing absorbers despite intrinsic limitations. The use of 3D/3D perovskite heterojunctions is also discussed as a means to achieve improved optical and electrical performance. Furthermore, advances in optical coatings and anti-reflective structures, along with the integration of photonic crystals and gratings into device architectures, are presented as emerging approaches for efficient nanoscale light management.

Coupled Optical–Electrical Design Challenges

The review explains that the optical challenges in APTSCs stem from intricate trade-offs among layer thickness, material composition, and spectral management. These factors must be carefully balanced so that each sub-cell absorbs its designated portion of sunlight while minimizing losses. Unlike single-junction devices, increasing absorber thickness is not always advantageous, as it can disrupt current matching within the tandem structure and increase parasitic absorption in adjacent layers. As a result, sophisticated optical simulations are essential for guiding precise control over these parameters.

The authors emphasize the importance of co-designing optical and electrical properties through multi-physics modeling, which integrates photonic, electronic, and thermal effects to better reflect real operating conditions. Such approaches offer deeper insight into complex phenomena, including light scattering caused by microstructural defects or grain boundaries in perovskite films, which can alter photon pathways and absorption profiles.

The review further highlights that implementing advanced light management strategies in practice requires scalable fabrication of nanostructures, transparent electrodes with low optical losses, and reliable interconnecting layers that minimize parasitic absorption. It notes that improved photon management not only enhances photocurrent but can also indirectly affect voltage and fill factor through its interaction with recombination and charge transport processes, rather than serving as the sole performance driver.

Ongoing challenges are also addressed, particularly the relatively low absorption coefficients of NBG perovskites in the near-infrared region, coupled with high defect densities that limit carrier lifetimes. Overcoming these limitations through coordinated material engineering and optical optimization will be critical for pushing efficiencies beyond 30% in monolithic tandem perovskite devices.

The Path Forward for Perovskite Tandem Photovoltaics

In conclusion, the review notes that despite the technical complexities, ongoing advances in light management, such as improved anti-reflection coatings, nanophotonic structures, electrode engineering, and interface passivation, are steadily enhancing PCE and supporting the path toward scalable, high-efficiency devices. It also acknowledges the rapid progress APTSCs have made since their inception, with efficiencies now approaching levels that were previously out of reach.

The article expresses cautious optimism that continued interdisciplinary research will address the remaining challenges, enabling scalable fabrication and integration of highly efficient, stable all-perovskite tandem solar cells into future energy systems. At the same time, it emphasizes that further optimization and manufacturing advances remain necessary.

Overall, the study underscores the central role of optical design in unlocking the full potential of perovskite tandem photovoltaics and positioning them as a key contributor to future solar energy landscapes.

Want to explore further? You might look into topics such as tandem solar cell stability, scalable fabrication techniques for perovskites, or emerging nanophotonic strategies for light trapping in next-generation photovoltaics.