At present, the mainstream organic-inorganic hybrid perovskite solar cell devices mainly have two kinds of structures, namely a porous structure and a planar structure. In both of these structures, the organic-inorganic hybrid perovskites are based on polycrystalline nano-thin films, whose photoelectric conversion efficiency has exceeded 20%.
For organic-inorganic hybrid perovskite systems, the optoelectronic properties of single crystal devices are much better than those of nanocrystalline thin film devices currently widely used. It is mainly due to the reduction of the number of defects in the grain boundary and the like in the single crystal sample, which greatly increases the probability that the photo-generated carriers reach the electrodes on both sides of the device, thereby increasing the photocurrent density of the device.
Xu Jinbao, a researcher at the Xinjiang Institute of Physics and Chemistry at the Chinese Academy of Sciences, led his research team to discover a simple method for the preparation of CH3NH3PbBr3 large-size single crystals.
This method uses a single solvent precursor, which is simple, low-cost, and can be completed at room temperature. This method has been used to grow a 14Ã—14mm large-size crystal. The crystal has a cubic phase structure. P-43m(215) Space group; This single crystal is weak in spontaneous polarization in the dark state. Under light conditions, the crystal shows a clear spontaneous polarization of the surface, reflecting the characteristics of light-induced polarization; in the light and dark state, the surface The difference in potential is as high as 200mV, which is favorable for the preparation of high open-circuit voltage photoelectric conversion devices.
The current distribution on the surface of the single crystal is uniform, and the photocurrent is about 20 times that of the dark state current, and there is no attenuation on the entire surface. This result indicates that the single-crystal hybrid perovskite device is promising compared with the current nanocrystalline thin film device. Greatly increase its photocurrent density.
The research results were published in the Journal of Physical Chemistry Letters, and related research work was funded by the "Thousand Person Project" - the Xinjiang Special Project, the National Natural Science Foundation of China, and the Western Light of the Chinese Academy of Sciences.
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