Preparation Of CQDs/TiO₂ Composite And Its Application In Inorganic Perovskite Solar Cells

In this paper,CQDs/TiO₂ materials and their applications as CsPbI₂Br inorganic perovskite solar cells were studied.Carbon quantum dots were prepared by calcination method,and CQDs/TiO₂ materials were prepared by hydrothermal method.The CQDs/TiO₂ film and the CsPbI2Br inorganic perovskite film were sequentially prepared on the FTO substrate by spin coating+annealing.Apply it to the electron transport layer.The microstructure,phase composition and microstructure of the products prepared by different processes were characterized by XRD,SEM,TEM and infrared spectroscopy.The optical properties of the materials were characterized by UV-Vis spectrometry and photoluminescence.Characterize and test the device JV curve to characterize its photovoltaic performance.The effect of CQDs/TiO₂ material as an electron transport layer on the photoelectric properties of perovskite solar cells was investigated.In this paper,uniform size CQDs were obtained by one-step calcination.Nano-TiO₂ powder with good crystallinity and uniform particle size was prepared by TiCl₄ hydrolysis method.Through the hydrothermal reaction,CQDs and nano-TiO₂powders were used as raw materials.By changing the parameters of temperature,time and raw material mass ratio of hydrothermal reaction,CQDs/TiO₂ composites with controlled morphology and different optical properties were obtained.The CsPbI₂Br perovskite film was prepared by spin coating method and secondary annealing method as the light absorbing layer.The effects of step annealing time on the morphology and optical properties of CsPbI2Br film were studied,and the CsPbI₂Br film with good surface quality was obtained.The conventional perovskite solar cell device was prepared by using TiO₂ as electron transport material.The JV curve of the test device was used to characterize its photovoltaic performance.The short circuit current of the optimal device was 11.26mA/cm²,the open circuit voltage was 0.96V,and the obtained photoelectric conversion efficiency was 4.39%.Further,six kinds of CQDs/TiO₂ films were prepared as electron transport layers,CsPbI₂Br as photoactive layer and Spiro-OMeTAD as hole transport layer.The structure was FTO/?CQDs/TiO₂?/CsPbI2Br/Spiro.The solar cell device of-OMeTAD/Au has an optimum photoelectric conversion efficiency of 5.01%.The photoelectric conversion efficiency is up to 12.3%higher than that of the conventional TiO₂ as the electron transport layer.