Time-resolved, nonequilibrium carrier dynamics in Si-on-glass thin films for photovoltaic cells

ABSTRACTContactless photoconductivity measurements with the time-resolved microwave conductivity technique have been performed during the growth of hydrogenated amorphous silicon films. it has been shown that low substrate temperature and thin films lead to a larger electron decay rate and to an increased infrared absorption compared with high quality films. Addition of H2S to SiH4 during the glow discharge process leads to a worse fi1m quality which can be detected in-situ.

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Effects of Crystal Morphology on the Hot-Carrier Dynamics in Mixed-Cation Hybrid Lead Halide Perovskites

Energies ◽

10.3390/en14030708 ◽

2021 ◽

Vol 14 (3) ◽

pp. 708

Author(s):

Daniele Catone ◽

Giuseppe Ammirati ◽

Patrick O’Keeffe ◽

Faustino Martelli ◽

Lorenzo Di Mario ◽

...

Keyword(s):

High Sensitivity ◽

Carrier Dynamics ◽

Large Area ◽

Photovoltaic Properties ◽

Time Resolved ◽

Hot Carrier ◽

Mixed Cation ◽

Small Crystals ◽

Characterization Of Materials ◽

Lead Halide

Ultrafast pump-probe spectroscopies have proved to be an important tool for the investigation of charge carriers dynamics in perovskite materials providing crucial information on the dynamics of the excited carriers, and fundamental in the development of new devices with tailored photovoltaic properties. Fast transient absorbance spectroscopy on mixed-cation hybrid lead halide perovskite samples was used to investigate how the dimensions and the morphology of the perovskite crystals embedded in the capping (large crystals) and mesoporous (small crystals) layers affect the hot-carrier dynamics in the first hundreds of femtoseconds as a function of the excitation energy. The comparative study between samples with perovskite deposited on substrates with and without the mesoporous layer has shown how the small crystals preserve the temperature of the carriers for a longer period after the excitation than the large crystals. This study showed how the high sensitivity of the time-resolved spectroscopies in discriminating the transient response due to the different morphology of the crystals embedded in the layers of the same sample can be applied in the general characterization of materials to be used in solar cell devices and large area modules, providing further and valuable information for the optimization and enhancement of stability and efficiency in the power conversion of new perovskite-based devices.

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Superior photo-carrier diffusion dynamics in organic-inorganic hybrid perovskites revealed by spatiotemporal conductivity imaging

Nature Communications ◽

10.1038/s41467-021-25311-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Xuejian Ma ◽

Fei Zhang ◽

Zhaodong Chu ◽

Ji Hao ◽

Xihan Chen ◽

...

Keyword(s):

Thin Films ◽

Solar Cell ◽

Relaxation Times ◽

Charge Trapping ◽

Free Carrier ◽

Carrier Dynamics ◽

Electron Hole ◽

Inorganic Hybrid ◽

Diffusion Dynamics ◽

The Difference

AbstractThe outstanding performance of organic-inorganic metal trihalide solar cells benefits from the exceptional photo-physical properties of both electrons and holes in the material. Here, we directly probe the free-carrier dynamics in Cs-doped FAPbI3 thin films by spatiotemporal photoconductivity imaging. Using charge transport layers to selectively quench one type of carriers, we show that the two relaxation times on the order of 1 μs and 10 μs correspond to the lifetimes of electrons and holes in FACsPbI3, respectively. Strikingly, the diffusion mapping indicates that the difference in electron/hole lifetimes is largely compensated by their disparate mobility. Consequently, the long diffusion lengths (3~5 μm) of both carriers are comparable to each other, a feature closely related to the unique charge trapping and de-trapping processes in hybrid trihalide perovskites. Our results unveil the origin of superior diffusion dynamics in this material, crucially important for solar-cell applications.

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