Identification and Dynamics of Microsecond Long-Lived Charge Carriers for CsPbBr₃ Perovskite Quantum Dots, Featuring Ambient Long-Term Stability

We analyze the stability and photophysical dynamics of CsPbBr₃ perovskite quantum dots (PeQDs), fabricated under mild synthetic conditions and embedded in an amorphous silica (SiO_x) matrix (CsPbBr₃@SiO_x), underscoring their sustained performance in ambient conditions for over 300 days with minimal optical degradation. However, this stability comes at the cost of a reduced photoluminescence efficiency. Time-resolved spectroscopic analyses, including flash-photolysis time-resolved microwave conductivity and time-resolved photoluminescence, show that excitons in CsPbBr₃@SiO_x films decay within 2.5 ns, while charge carriers recombine over approximately 230 ns. This longevity of the charge carriers is due to photoinduced electron transfer to the SiO_x matrix, enabling hole retention. The measured hole mobility in these PeQDs is 0.880 cm² V^-1 s^-1, underscoring their potential in optoelectronic applications. This study highlights the role of the silica matrix in enhancing the durability of PeQDs in humid environments and modifying exciton dynamics and photoluminescence, providing valuable insights for developing robust optoelectronic materials.