Marjit Kritiman, Ghosh Goutam, Ghosh Srijon, Ghosh Debarati, Medda Anusri, Patra Amitava
School of Materials Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
Institute of Nano Science and Technology, Knowledge City, Sector 81, Mohali 140306, India.
ACS Phys Chem Au. 2023 Feb 28;3(4):348-357. doi: 10.1021/acsphyschemau.2c00070. eCollection 2023 Jul 26.
Lead halide perovskite nanocrystals have received significant attention as an absorber material for designing efficient optoelectronic devices. The fundamental understanding of the hot carrier (HC) dynamics as well as its extraction in hybrid systems is essential to further boost the performance of solar cells. Herein, we have explored the electron transfer dynamics in the CsPbBr-Au cluster hybrid using ultrafast transient absorption spectroscopy. Our analysis reveals faster HC cooling time (from 515 to 334 fs) and a significant drop in HC temperature from 1055 to 860 K in hybrid, suggesting the hot electron transfer from CsPbBr nanocrystals to the Au nanoclusters (NCs). Eventually, we observe a much faster hot electron transfer compared to the band-edge electron transfer, and 45% hot-electron transfer efficiency was achieved at 0.64 eV, above band-edge photoexcitation. Furthermore, the significant enhancement of the photocurrent to the dark current ratio in this hybrid system confirms the charge separation via the electron transfer from CsPbBr nanocrystals to Au NCs. These findings on HC dynamics could be beneficial for optoelectronic devices.
卤化铅钙钛矿纳米晶体作为一种用于设计高效光电器件的吸收材料受到了广泛关注。深入了解热载流子（HC）动力学及其在混合体系中的提取对于进一步提高太阳能电池的性能至关重要。在此，我们利用超快瞬态吸收光谱研究了CsPbBr-Au团簇混合体系中的电子转移动力学。我们的分析表明，混合体系中HC冷却时间更快（从515飞秒降至334飞秒），HC温度从1055开尔文大幅降至860开尔文，这表明热电子从CsPbBr纳米晶体转移到了Au纳米团簇（NCs）。最终，我们观察到与带边电子转移相比，热电子转移速度要快得多，在高于带边光激发的0.64电子伏特下，实现了45%的热电子转移效率。此外，该混合体系中光电流与暗电流之比的显著提高证实了通过电子从CsPbBr纳米晶体转移到Au NCs实现了电荷分离。这些关于HC动力学的发现可能对光电器件有益。
