We show the mechanical strengthening of the buried interface in perovskite solar cells by using a cohesive macromolecular binder. Solar cells with a strengthened interface delivered a T97.5 lifespan of over 1600 h under 1-sun illumination at 55 °C.
Abstract Understanding the degradation mechanism of perovskite solar cells (PSCs) is of particular importance to solve their instability issue, which is one of the major hindrances toward commercialization. Here, it is shown that a halide diffusion equilibrium exists at the heterointerface of perovskite devices, which strongly impacts the evolution of device performance. The combined experimental and theoretical studies reveal that halide components diffuse from perovskite to fullerene layers in a p‐i‐n PSC device and equilibrate with an iodine density of 10 18 –10 19 cm −3 within 80 h under dark aging condition. It is found that there is a strong correction between the device efficiency and halide diffusion equilibrium of PSCs, as the diffused halides can chemically dope the transport layer and result in the nonstoichiometric perovskite surface, leading to both initial enhancement and long‐term loss of the photovoltaic efficiency of solar cells. In response to this issue, a predoping strategy is developed to attain the halide diffusion equilibrium once the device is fabricated, thereby avoiding the further halide migration and initial efficiency variations. As a result, the as‐prepared PSC achieved an efficiency of 23.13% as well as stable power output under continuous one sun illumination.
Abstract Metal-halide perovskite thin monocrystals featuring efficient carrier collection and transport capabilities are well suited for radiation detectors, yet their growth in a generic, well-controlled manner remains challenging. Here, we reveal that mass transfer is one major limiting factor during solution growth of perovskite thin monocrystals. A general approach is developed to overcome synthetic limitation by using a high solute flux system, in which mass diffusion coefficient is improved from 1.7×10 –10 to 5.4×10 –10 m 2 s –1 by suppressing monomer aggregation. The generality of this approach is validated by the synthesis of 29 types of perovskite thin monocrystals at 40–90 °C with the growth velocity up to 27.2 μm min –1 . The as-grown perovskite monocrystals deliver a high X-ray sensitivity of 1.74×10 5 µC Gy −1 cm −2 without applied bias. The findings regarding limited mass transfer and high-flux crystallization are crucial towards advancing the preparation and application of perovskite thin monocrystals.
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