TY - JOUR
T1 - Cation-Dependent Hot Carrier Cooling in Halide Perovskite Nanocrystals
AU - Chen, Junsheng
AU - Messing, Maria E.
AU - Zheng, Kaibo
AU - Pullerits, Tonu
PY - 2019/2/27
Y1 - 2019/2/27
N2 - Lead halide perovskites (LHPs) nanocrystals (NCs), owing to their outstanding photophysical properties, have recently emerged as a promising material not only for solar cells but also for lighting and display applications. The photophysical properties of these materials can be further improved by chemical engineering such as cation exchange. Hot carrier (HC) cooling, as one of the key photophysical processes in LHPs, can strongly influence performance of LHPs NCs based devices. Here, we study HC relaxation dynamics in LHP NCs with cesium (Cs), methylammonium (MA, CH 3 NH 3 + ), and formamidinium (FA, CH(NH 2 ) 2 + ) cations by using femtosecond transient absorption spectroscopy. The LHP NCs show excitation intensity and excitation energy-dependent HC cooling. We investigate the details of HC cooling in CsPbBr 3 , MAPbBr 3 , and FAPbBr 3 at three different excitation energies with low excitation intensity. It takes longer time for the HCs at high energy to relax (cool) to the band edge, compared to the HCs generated by low excitation energy. At the same excitation energy (350 nm, 3.54 eV), all the three LHP NCs show fast HC relaxation (<0.4 ps) with the cooling time and rate in the following order: CsPbBr 3 (0.39 ps, 2.9 meV/fs) > MAPbBr 3 (0.27 ps, 4.6 meV/fs) > FAPbBr 3 (0.21 ps, 5.8 meV/fs). The cation dependence can be explained by stronger interaction between the organic cations with the Pb-Br frameworks compared to the Cs. The revealed cation-dependent HC relaxation process is important for providing cation engineering strategies for developing high performance LHP devices.
AB - Lead halide perovskites (LHPs) nanocrystals (NCs), owing to their outstanding photophysical properties, have recently emerged as a promising material not only for solar cells but also for lighting and display applications. The photophysical properties of these materials can be further improved by chemical engineering such as cation exchange. Hot carrier (HC) cooling, as one of the key photophysical processes in LHPs, can strongly influence performance of LHPs NCs based devices. Here, we study HC relaxation dynamics in LHP NCs with cesium (Cs), methylammonium (MA, CH 3 NH 3 + ), and formamidinium (FA, CH(NH 2 ) 2 + ) cations by using femtosecond transient absorption spectroscopy. The LHP NCs show excitation intensity and excitation energy-dependent HC cooling. We investigate the details of HC cooling in CsPbBr 3 , MAPbBr 3 , and FAPbBr 3 at three different excitation energies with low excitation intensity. It takes longer time for the HCs at high energy to relax (cool) to the band edge, compared to the HCs generated by low excitation energy. At the same excitation energy (350 nm, 3.54 eV), all the three LHP NCs show fast HC relaxation (<0.4 ps) with the cooling time and rate in the following order: CsPbBr 3 (0.39 ps, 2.9 meV/fs) > MAPbBr 3 (0.27 ps, 4.6 meV/fs) > FAPbBr 3 (0.21 ps, 5.8 meV/fs). The cation dependence can be explained by stronger interaction between the organic cations with the Pb-Br frameworks compared to the Cs. The revealed cation-dependent HC relaxation process is important for providing cation engineering strategies for developing high performance LHP devices.
U2 - 10.1021/jacs.8b11867
DO - 10.1021/jacs.8b11867
M3 - Journal article
C2 - 30685969
SN - 0002-7863
VL - 141
SP - 3532
EP - 3540
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 8
ER -