# HKPU and Zhejiang University stabilize perovskite solar cells to 2,200 hours at 26.55% efficiency

- Published: 2026-11-06 13:10 UTC
- Section: Power & Energy › Energy
- Tags: perovskite solar cells, power conversion efficiency, photodegradation, grain boundaries, hetero facet defects, passivation
- URL: https://realtech.media/news/rt-27813bc7f3c2f0e271bdc3ff_hkpu_and_zhejiang/

**Researchers identified an asymmetric photodegradation pathway at crystal grain boundaries and passivated it with a fluorinated additive in prototype cells.**

![HKPU and Zhejiang University stabilize perovskite solar cells to 2,200 hours at 26.55% efficiency](https://sgzwpqqelzmajkcubgkl.supabase.co/storage/v1/object/public/rt-media/2026/11/d013e76e5d119fe1.jpg)
*Dennis Schroeder / National Renewable Energy Laboratory, Wikimedia Commons, Public domain*

Researchers from The Hong Kong Polytechnic University and Zhejiang University have identified a microscale degradation mechanism at crystal boundaries in polycrystalline perovskite solar cells, according to a study published in the journal Watt [1]. By applying a targeted chemical treatment to passivate facet-specific defects, the team produced prototype solar cells that achieved a power conversion efficiency of 26.55% and maintained over 90% of their performance after more than 2,200 hours of continuous one-sun illumination [1].

## Inter-grain defect mechanism

Polycrystalline perovskite films consist of microscopic grains with differing crystal facet orientations, such as (100) and (111). The researchers determined that hetero-facet grain boundaries induce an asymmetric inter-grain charge recombination pathway under illumination [1]. Despite the superior intrinsic photostability of the (111) facet, formamidinium vacancy defects concentrated at the (111) side of these boundaries caused a non-equilibrium accumulation of photogenerated positive charge carriers, or holes [1]. This localized imbalance accelerated photodegradation precisely at the hetero-facet interfaces.

## Targeted defect passivation

To suppress this degradation route, the authors introduced 3-fluorophenylethylammonium bromide (m-F-PEABr) into the material [1]. The compound targeted the identified formamidinium vacancies at the (111)-facet grain boundaries, effectively homogenizing carrier recombination across adjacent grains [1]. In laboratory tests under continuous one-sun conditions, treated prototype cells reached a T90 operational lifetime exceeding 2,200 hours alongside the 26.55% efficiency mark [1]. Further research is required to evaluate the performance of this interface stabilization strategy in large-area modules under fluctuating outdoor operating environments.

## Sources

1. [Watt](https://doi.org/10.1007/s44503-026-00013-1)
2. [knowridge.com](https://knowridge.com/2026/11/scientists-uncover-a-hidden-weakness-that-makes-promising-solar-cells-age)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-27813bc7f3c2f0e271bdc3ff_hkpu_and_zhejiang/