Mixed halide CsPb(Br_1-xI_x)₃ nanocrystals for green, orange, and red light-emitting diodes

Cesium lead halide (CsPbX₃; X = Cl, Br, and I)-based nanocrystals (NCs) are an attractive optoelectronic material for next-generation lighting and display applications. Except for green-emitting CsPbBr₃-based NCs, however, there are few investigations for another visible wavelength spectral-ranged color emitters, such as yellow, orange, and red light-emitting diodes (LEDs). This paper reports a facile synthesis of CsPb(Br_1-xI_x)₃ NCs emitting wavelengths from green to red based on a halide exchange post-treatment using a trimethylsilyl iodide (TMSI) additive. Microstructural and optical investigations showed that the TMSI modulated the iodine content of CsPb(Br_1-xI_x)₃ NCs, resulting in a successive shift of photoluminescence peaks from 510 to 663 nm. Based on CsPb(Br_1-xI_x)₃ NCs, LEDs emitting from green to red wavelengths were demonstrated. Interestingly, CsPb(Br_1-xI_x)₃ NCs exhibited abnormal electroluminescence (EL) spectra, showing a large red-shift and additional peaks corresponding to the pristine CsPbBr₃ NCs. These were attributed to the modification of CsPb(Br_1-xI_x)₃ NCs during the LED fabrication process as well as electrical field-induced phase-segregation during operation.