Grain Boundary Investigation in Perovskite Solar Cells

Grain boundaries in polycrystalline perovskite films represent critical interfaces where defects congregate, influencing charge transport, recombination and long‐term device stability. These narrow junctions may act as benign conduits enhancing carrier separation or as recombination centres that undermine performance. Contemporary efforts seek to resolve the dual nature of grain boundaries by correlating nanoscale structure with optoelectronic function, exploring how local chemistry, strain and ionic motion modulate barrier heights and defect densities. Understanding these interfaces is pivotal for scaling perovskite photovoltaics, as passivation strategies and additive engineering aim to neutralise deleterious defect states, suppress ion migration and preserve high power conversion efficiency under operational stresses.

Research from Nature Portfolio

Studies have quantitatively imaged charge transport at grain boundaries, revealing that two distinct boundary types can coexist: one exhibiting enhanced carrier mobility and another showing negligible conduction. Three‐dimensional tomographic atomic force microscopy has uncovered interconnected conducting channels that traverse buried grain boundaries, overturning the paradigm that all grain interfaces are detrimental. Investigations of model methylammonium lead triiodide films demonstrate that degradation initiates within grain interiors rather than at visible boundary lines, highlighting bulk crystallinity as a key determinant of stability. Spatiotemporal photoconductivity mapping in doped formamidinium‐cesium perovskites has further shown that both electrons and holes possess long diffusion lengths (several micrometres) and comparable lifetimes, a feature intimately tied to trap‐mediated de‐trapping dynamics at grain boundaries that compensate for mobility differences and underpin high device performance.

Grain Boundary Investigation in Perovskite Solar Cells publication trend

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

Technical terms

Grain boundary: The interface between two crystalline domains in a polycrystalline film, often hosting defects and altered electronic properties.

Passivation: The process of chemically or physically neutralising defect states at surfaces or interfaces to reduce non‐radiative recombination.

Recombination centre: A defect or trap site where electrons and holes recombine non‐radiatively, reducing photocurrent.

Kelvin probe force microscopy (KPFM): A scanning probe technique measuring local surface potential and work‐function variations with nanometre resolution.

Photoconductivity: The increase in electrical conductivity of a material upon illumination due to generation of charge carriers.

Ion migration: The movement of ionic species within the perovskite lattice under electric field or illumination, affecting long‐term stability and hysteresis.

References

1. The Role of Grain Boundaries in Organic–Inorganic Hybrid Perovskite Solar Cells and its Current Enhancement Strategies: A Review. Energy & Environmental Materials (2024).
2. Impact of grain boundaries on efficiency and stability of organic-inorganic trihalide perovskites. Nature Communications (2017).
3. Anomalous 3D nanoscale photoconduction in hybrid perovskite semiconductors revealed by tomographic atomic force microscopy. Nature Communications (2020).
4. Electronic Properties of {111} Twin Boundaries in a Mixed-Ion Lead Halide Perovskite Solar Absorber. ACS Energy Letters (2018).
5. Quantification of electron accumulation at grain boundaries in perovskite polycrystalline films by correlative infrared-spectroscopic nanoimaging and Kelvin probe force microscopy. Light: Science & Applications (2021).
6. Superior photo-carrier diffusion dynamics in organic-inorganic hybrid perovskites revealed by spatiotemporal conductivity imaging. Nature Communications (2021).