Electron Transport Materials in Perovskite Solar Cells

Perovskite solar cells have rapidly advanced towards high efficiency and low-cost manufacture, largely owing to developments in electron transport materials (ETMs) that facilitate extraction and conduction of photo-generated electrons. In both n–i–p and p–i–n device architectures, the ETM forms a critical interface with the perovskite absorber, where optimised energy-level alignment, high electron mobility and minimal trap states are essential for maximising power conversion efficiency and operational stability. Conventional fullerene derivatives, such as C60 and phenyl-C61-butyric acid methyl ester (PCBM), offer suitable electronic properties and facile deposition, but suffer from morphological instability and limited tunability. Emerging non-fullerene small molecules, conjugated polymers and naphthalene- or perylene-diimide scaffolds have broadened the palette of available ETMs, providing enhanced chemical robustness, tailored band alignment and improved trap passivation. The continued refinement of purification protocols, molecular design and interface engineering is crucial for translating perovskite photovoltaics into scalable, commercially viable technologies with reproducible performance and long-term resilience under operational stresses.

Research from Nature Portfolio

Recent studies have demonstrated that the purity of thermally evaporated C60 can dramatically influence device reproducibility and performance. It was shown that oxygen impurities in as-received C60 coalesce during repeated evaporation, generating deep sub-bandgap states that diminish open-circuit voltage and fill factor. Sublimation purification of C60 to a higher grade prior to deposition suppresses this coalescence, ensuring consistent electron transport layer morphology and yielding fully reproducible perovskite/silicon tandem cells with open-circuit voltages around 1.95 V, fill factors above 81 % and a certified power conversion efficiency exceeding 30.9 %. These findings underscore the importance of source-material quality control for scaled production of perovskite photovoltaics with high process yield.

Electron Transport Materials in Perovskite Solar Cells publication trend

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

Technical terms

Electron transport layer (ETL): A functional film that collects and conducts electrons from the light-absorbing perovskite to the cathode while blocking holes.

Band alignment: The relative energy positions of the conduction and valence bands (or molecular orbitals) at an interface, crucial for efficient charge extraction.

Trap states: Defect levels within the semiconductor bandgap that can capture charge carriers and promote non-radiative recombination.

Power conversion efficiency (PCE): The ratio of electrical power output to incident solar power under standard illumination conditions.

Electron mobility: A measure of the ease with which electrons move through a material under an applied electric field, expressed in cm2 V–1 s–1.

References

1. Julolidine functionalized benzimidazoline‐doped fullerene derivatives for efficient and stable perovskite solar cells. Interdisciplinary Materials (2024).
2. Sublimed C60 for efficient and repeatable perovskite-based solar cells. Nature Communications (2024).
3. Solution-processable perylene diimide-based electron transport materials as non-fullerene alternatives for inverted perovskite solar cells. Journal of Materials Chemistry A (2022).
4. Rational Design of Lewis Base Electron Transport Materials for Improved Interface Property in Inverted Perovskite Solar Cells: A Theoretical Investigation. Nanomaterials (2023).