Perovskite nanomaterials have emerged as new class of photonic materials with promising applications in solar cells and LEDs. Strong light absorption, halide dependent tunable band gap, exceptionally high photoluminescence, and excellent charge transport properties, photostable, long carrier lifetime, facilitating highly efficient light-to-electricity conversion have attracted the attention for photonic and optoelectronic device applications. Lately, hybrid-dimensional nano-heterostructures have shown promise as optoelectronic materials. In this study, interaction between carbon dots and a series of CsPbX3 perovskites (Figure 1) is studied with steady-state and ultrafast time-resolved spectroscopy. Amalgamation of CsPbX3 nanocrystals with the zero-dimensional carbon dots has not yet been investigated. Carbon dots (CDs) have unique electrical, optical, and chemical properties. CDs were synthesized with pyrene as precursor using hydrothermal method and characterized. The synthesized CDs (positive and negatively charged) are soluble in water and in an effort to study the interaction between CDs and Perovskites, phase transfer to organic solvent is performed using surfactants. Steady-state photoluminescence of CsPbX3 (X3 = Br3, Br2Cl, BrI2; except CsPbCl3) was observed in the presence of CDs. The quenching seems to be arising from static quenching where in the CD and Perovskite forming a complex as the PL lifetimes are unchanged with the addition of CDs. Ultrafast transient absorption measurements were able to shed light on the charge-transfer relaxation between perovskites and CDs. Based on the halide composition, perovskites have differing band gaps and there is a correlation between the charge-transfer lifetimes and bandgap. Observed charge-transfer rates are modeled with existing theories.

Ultrafast interfacial charge-transfer relaxation between carbon Dots and CsPbX3 nanocrystals

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