Effect of reaction temperature on CsPbBr3 perovskite quantum dots with photovoltaic applications

Solar energy has been relevant in recent years as a renewable source. On one side, halide perovskites have played an essential role as semiconductors with photovoltaic applications. This work studied the effect of reaction temperature on the synthesis of CsPbBr3 perovskite quantum dots (PQDs) by the hot injection method. In this case, CsPbBr3 PQDs are very stable compared to other halide perovskites. The XRD analysis indicated three crystalline phases were obtained: cubic of CsPbBr3, orthorhombic, and rhombohedral of Cs4PbBr6. At a temperature of 130 °C, the cubic phase predominates at 57%. When the temperature increases to 155 and 180 °C, the cubic phase is obtained to a lesser extent, with 33% and 10%, respectively, and the orthorhombic and rhombohedral phases increase. SEM reveals that particle size increased from 8 to 36 nm due to the reaction temperature. The UV-vis results showed that the absorption spectra had a redshift of the visible spectrum from an absorption band from 487 to 514 and 522 nm. Likewise, the PL spectra demonstrate a peak of 501 to 517 and 515 nm as a function of temperature increase, where the calculated Full Width at Half Maximum (FWHM) indicates the purity of the color emitted. Tauc plots of the CsPbBr3 PQDs showed band gap energies between 1.64 to 2.37 eV, which means these PQDs are interesting in photovoltaics. On the other hand, solar cells were fabricated using CsPbBr3 PQDs, with the following architecture: FTO/c-TiO2/m-TiO2/PQDs/spiro-OMeTAD/Ag. The photovoltaic parameters were determined, obtaining with Jsc (4.10·10-6 mA·cm-2), Voc (0.434 V), FF (30.56%), and PCE (5·10-4 %). In conclusion, the obtained PVs indicated the charge transport within the solar device in ambient conditions.