Optical Properties of Perovskite Solar Cells

Hybrid lead halide perovskites have emerged as a leading contender in photovoltaic research on account of their exceptional light‐matter interactions. Their high absorption coefficients, tunable bandgaps and long carrier diffusion lengths combine to yield strong optical harvesting across the visible and near-infrared spectrum. Key to their performance is the complex refractive index, which governs internal reflection, transmission and parasitic losses. Temperature and compositional variations induce phase transitions that modulate band edge energies and exciton behaviour, while nano-structuring and antireflection strategies aim to mitigate optical losses at interfaces. Advances in modelling and experimental metrology, including spectroscopic ellipsometry and transfer-matrix simulations, have elucidated the interplay between film morphology, dielectric function and device architecture. This has underpinned concerted efforts to engineer perovskite layers and optical coatings that maximise light capture, minimise reflection and maintain stability under operational stresses.

Research from Nature Portfolio

Recent studies have employed temperature-dependent ellipsometry to reveal how mixed cation perovskite single crystals exhibit shifts in bandgap and exciton binding energy as they undergo structural phase transitions. As temperature decreases from ambient to cryogenic values, the refractive index increases and distinct excitonic peaks sharpen, reflecting changes in electronic ordering. An anomaly in the thermo-optic coefficient around 100–200 K has been linked to coexistence of ordered and disordered cation domains. These insights provide a benchmark for controlling optical dispersion in lead halide perovskites and inform the design of photonic devices operating across a wide temperature range.

Optical Properties of Perovskite Solar Cells publication trend

The graph below shows the total number of articles in optical properties of perovskite solar cells across all publications each year (not limited to Nature Index journals).

Technical terms

Refractive index: A dimensionless number expressing how much light slows down in a material compared with vacuum.

Extinction coefficient: The imaginary part of the refractive index, representing the material’s intrinsic light absorption per unit distance.

Spectroscopic ellipsometry: A non-destructive optical technique that measures changes in polarisation upon reflection to extract complex dielectric functions and film thicknesses.

Transfer-matrix method: A computational approach to model light propagation through stratified media by accounting for multiple reflections and interference.

Exciton binding energy: The energy required to separate an electron–hole pair bound by Coulomb attraction within a semiconductor.

References

1. Optical simulations and optimization of perovskite/CI(G)S tandem solar cells using the transfer matrix method. Journal of Physics Energy (2023).
2. Ameliorating Properties of Perovskite and Perovskite–Silicon Tandem Solar Cells via Mesoporous Antireflection Coating Model. Advanced Electronic Materials (2023).
3. Determination of complex optical constants and photovoltaic device design of all-inorganic CsPbBr3 perovskite thin films.. Optics Express (2020).
4. Characterizing temperature-dependent optical properties of (MA0.13FA0.87) PbI3 single crystals using spectroscopic ellipsometry. Scientific Reports (2019).