Discerning the Ultrafast Charge Dynamics in Photostable Perovskite-Carbon Dot Composite Systems: Role of Doped Carbon Dots

Abstract

Photostable perovskite quantum dot (PQD)-based composite systems have huge potential for optoelectronic and photocatalysis applications. Herein, we have synthesized hydrophobic carbon dots (NC-Dots) and made a composite system with PQD to improve the stability of the material and establish a new generation of advanced materials for future applications. However, there is a lack of fundamental understanding of the dynamics and charge separation mechanism in PQD and NC-Dot-based composite systems, which is essential to interpret the degree of efficiency. In this context, we have also synthesized composites of PQD and different co-doped (boron and phosphorus) NC-Dots to explore the complete scenario of carrier dynamics. This would help in finding the appropriate composite system for photocatalysis. The ultrafast studies show that the carrier-transfer process depends on the dopant of the NC-Dots. The PQD-NC-Dots and PQD-phosphorus doped-NC-Dots (PQD-P-NC-Dots) tend to demonstrate unidirectional carrier transfer, while the PQD-boron-doped C-Dots (PQD-B-NC-Dots) are found to be bidirectional carrier-transfer in the hot states. This is the first investigation on the effect of doped NC-Dots on the multiexciton dissociation in the PQD composite systems that showed a direct relationship with the photocatalytic efficiency. This proof of concept in multielectron dissociation and directional carrier transfer may provide a new approach to improve the efficiency in optoelectronics, photocatalysis, and other similar applications.

Efficient Charge Transfer in the Perovskite Quantum Dot–Hemin Biocomposite: Is This Effective for Optoelectronic Applications?

“…As per the literature, growth components of GSB signify the possibility of carrier cooling through two different ways and two major ultrafast decay components (τ 1d = 5 ps and τ 2d = 200 ps), and a slow component (τ 3d > 1 ns) appears from the carrier-trapping and recombination process. 27 We observed that the lifetime of the growth component (τ 2g = 0.7 ps) in the PQD−hemin composite becomes slower than that of the PQDs (τ 2g = 0.3 ps), which signifies that the excited state is more populated in the composite system as a result of the resonance of the vibration levels between PQDs and hemin in the excited state. Hot carrier transfer and delocalization of the carriers from hemin toward PQD states can be held liable for such delayed dynamics when the pump energy is high.…”

“…25,26 In our previous work, we observed that electron transfer was more facile in the PQD−NC dot composite systems, but the process became slower upon the co-doping of P and B in the NC dots as a result of the formation of new PN and BN hybrid states, respectively. 27 Lian's group reported carrier dynamics, such as the carrier-trapping and recombination process and interfacial charge-transfer process within zerodimensional (0D) and two-dimensional (2D) PQDs and molecular electron and hole acceptors. 28,29 Mn-doped perovskites were the most widely reported PQD-based doped materials as a result of their interesting optical, electronic, and magnetic properties.…”

“…9−13 Recently, our group developed PQD-based composite systems with different (nitrogen, boron, and phosphorus)-doped carbon dots, where PQDs and nitrogendoped carbon dots (NC dots) show higher photocatalytic activity than other composite systems. 14 In this context, apart from metal oxide, different chalcogenide semiconductors (PbS, PbSe, Cdse, CdS, and ZnS) have been employed to form the PQD-based heterostructure for tailoring the photoresponse properties. 3,15−17 Devices made from the CsPbBr 3 −PbS composite system show the responsivity up to 4.5 × 10 5 A W −1 , which was highly efficient compared to the individual material-based devices.…”

“…Moreover, PQD-based heterostructures were formed after coupling with different metal oxides and semiconductors to form the type I or II heterostructures based on their bandgap alignment. Recently, type II heterojunction composites, such as CsPbBr 3 /TiO 2 , CsPbBr 3 /ZrO 2 , CsPbBr 3 /ZnO, and CsPbBr 3 /graphene oxide, have been reported for photovoltaic and photocatalytic application with enhanced performance compared to CsPbBr 3 . − Recently, our group developed PQD-based composite systems with different (nitrogen, boron, and phosphorus)-doped carbon dots, where PQDs and nitrogen-doped carbon dots (NC dots) show higher photocatalytic activity than other composite systems . In this context, apart from metal oxide, different chalcogenide semiconductors (PbS, PbSe, Cdse, CdS, and ZnS) have been employed to form the PQD-based heterostructure for tailoring the photoresponse properties. ,− Devices made from the CsPbBr 3 –PbS composite system show the responsivity up to 4.5 × 10 5 A W –1 , which was highly efficient compared to the individual material-based devices .…”

Electron Transfer from an Optically Pumped Polyhedral Perovskite Nanocrystal to Pristine Fullerene

“…8−12 However, similar studies with polyhedral PNCs are largely missing in the literature because of their recent entry. 13,14 Here, we performed a solution phase bimolecular photoinduced charge transfer study in a hybrid of 12…”