Marjit Kritiman, Ghosh Goutam, Biswas Raju K, Ghosh Srijon, Pati Swapan K, Patra Amitava
School of Materials Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India.
Theoretical Sciences Unit, School of Advanced Materials (SAMat), Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore 560064, India.
J Phys Chem Lett. 2022 Jun 23;13(24):5431-5440. doi: 10.1021/acs.jpclett.2c01270. Epub 2022 Jun 9.
Manipulation of intrinsic carrier relaxation is crucial for designing efficient lead halide perovskite nanocrystal (NC) based optoelectronic devices. The influence of heterovalent Bi doping on the ultrafast carrier dynamics and hot carrier (HC) cooling relaxation of CsPbBr NCs has been studied using femtosecond transient absorption spectroscopy and first-principles calculations. The initial HC temperature and LO phonon decay time point to a faster HC relaxation rate in the Bi-doped CsPbBr NCs. The first-principles calculations disclose the acceleration of carrier relaxation in Bi-doped CsPbBr NCs due to the appearance of localized bands (antitrap states) within the conduction band. The higher Born effective charges (*) and higher soft energetic optical phonon density of states cause higher electron-phonon scattering rates in the Bi-doped CsPbBr system, which is responsible for the faster HC cooling rate in doped systems.
控制本征载流子弛豫对于设计基于高效铅卤化物钙钛矿纳米晶体（NC）的光电器件至关重要。利用飞秒瞬态吸收光谱和第一性原理计算，研究了异价Bi掺杂对CsPbBr纳米晶体超快载流子动力学和热载流子（HC）冷却弛豫的影响。初始热载流子温度和纵光学（LO）声子衰减时间表明，Bi掺杂的CsPbBr纳米晶体中热载流子弛豫速率更快。第一性原理计算表明，由于导带内出现局域带（反陷阱态），Bi掺杂的CsPbBr纳米晶体中载流子弛豫加速。较高的玻恩有效电荷（*）和较高的软能光学声子态密度导致Bi掺杂的CsPbBr系统中更高的电子-声子散射速率，这是掺杂系统中热载流子冷却速率更快的原因。
