🔍 This research investigates the hot carrier (HC) cooling dynamics in CsPbX3 (X = Br/Cl) nanocrystals (NCs) and explores how surface passivation with hexadecylamine (HDA) molecules affects these dynamics. Hot carriers are photo-excited charge carriers with excess energy above the bandgap, and controlling their cooling process is crucial for enhancing optoelectronic device efficiency.
Facts
- 🔹 Inorganic lead halide perovskites (CsPbX3) are used in optoelectronic applications due to their excellent properties.
- 🔹 Efficient optoelectronic devices depend on controlling photo-excited charge carrier dynamics.
- 🔹 Rapid cooling of hot carriers before energy loss is essential for high efficiency.
- 🔹 Substituting Cl ions for Br ions in CsPbBr3 nanocrystals has attracted attention.
- 🔹 Surface passivation can enhance stability and regulate carrier dynamics.
- 🔹 Surface ligands and passivating agents play roles in controlling hot carrier cooling.
- 🔹 Hexadecylamine (HDA) is explored as a passivating agent for CsPbX3 NCs.
📌 Inorganic lead halide perovskites (CsPbX3) have excellent properties that make them promising for optoelectronic applications. These properties include a wide absorption cross-section, tunable band gap, long carrier lifetime, high photoluminescence quantum yields (PLQYs), and good charge transport.
📌 Optoelectronic devices’ operation depends on the dynamics of photo-excited charge carriers, especially hot carriers (HCs). HCs are formed when excitation energy exceeds the band gap, and their rapid cooling is essential for energy conversion efficiency. Extracting HCs before they cool at the band-edge can lead to greater efficiency.
📌 Substituting Cl for Br ions in CsPbBr3 nanocrystals (NCs) has attracted interest due to the desired properties and improved stability it offers. However, the interplay between Cl-rich compositions and HC relaxation dynamics is less explored.
📌 Surface passivation, which reduces defects, can regulate HC cooling dynamics. Strategies like different ligands on the NC surface affect exciton relaxation dynamics and carrier-phonon coupling.
📌 Hexadecylamine (HDA) molecules are used for surface passivation due to their linear alkyl chain structure, which enhances stability. HDA’s electron-neutral nature is advantageous for charge-transfer processes.
📌 The study extensively investigates HC cooling dynamics in CsPbX3 (X = Br/Cl) NCs before and after HDA passivation using ultrafast transient absorption spectroscopy. Results show that increasing Cl content leads to faster ultrafast carrier relaxation dynamics.
📌 Interestingly, HDA-passivated CsPbX3 (X = Br/Cl) NCs exhibit slower ultrafast carrier relaxation dynamics and longer HC relaxation times. This suggests that HDA passivation delays HC cooling, which could enhance efficiency in optoelectronic applications.
- Antika Das, Kritiman Marjit, Srijon Ghosh, Debarati Ghosh, and Amitava Patra*
- Inorganic lead halide perovskites (CsPbX3) possess exceptional properties for optoelectronic applications.
- Efficient optoelectronic devices rely on controlling photo-excited charge carrier dynamics, including hot carriers (HCs).
- Surface passivation using hexadecylamine (HDA) can regulate HC cooling dynamics in CsPbX3 nanocrystals.
- Increasing Cl content in CsPbX3 nanocrystals leads to faster ultrafast carrier relaxation dynamics.
- HDA-passivated CsPbX3 nanocrystals show delayed HC cooling and could enhance efficiency in optoelectronic applications.
