Ultrafast photophysics in Mn-doped semiconductor quantum dots for optoelectronic application
Recent years witnessed a substantial improvement of solar cell technologies with the power conversion efficiencies of a variety of devices that can reach the thermodynamic limits (Shockley–Queisser Limit). However, in order to finally overcome the Shockley–Queisser Limit (≈33% for a standard cell with bandgap 1.4 eV), any process that will induce the heat loss of harvested photon energy should be well prevented. On the one hand, defects trapping of the excited charge carriers in the photovoltaic materials will result in non-radiative recombination and reduce the quantum efficiency of solar cells. On the other hand, rapid photo-generated hot‐carrier cooling is another primary channel for heat loss. The emerging metal ions doping in colloidal quantum dots (QDs) raises new opportunities to overcome Shockley–Queisser limitations. Such doping states could modulate not only the electronic structures but also the phonon structures of the QDs. Therefore, the main objective of the thesis is thereby to seek the feasibility of photophysical modulation on QDs by metal doping. In this thesis, we studied the photophysical properties of Mn-doped lead halide perovskite with a special focus on the exciton to dopant energy transfer and hot carrier cooling dynamics. This photophysical properties have a significant relationship with the doping. Our results show that the both electronic structure and the crystal structures are modified by Mn doping in the perovskite structure, which both act as critical factors in determining the charge carrier dynamics.