The vapor transport deposition of quasi‐one‐dimensional antimony selenosulfide (Sb2(S,Se)3) has recently attracted increasing research interest for the inexpensive, high‐throughput production of thin film photovoltaic devices. Further improvements in Sb2(S,Se)3 solar cell performance urgently require the identification of processing strategies to control the orientation, however the growth mechanism of high quality absorbers is still not completely clear. Herein, a facile and general vapor transport deposition approach to precisely control the growth of large‐grained dense Sb2(S,Se)3 films with good crystallization and preferred orientation via the source vapor speed is utilized. It is found that defect activation energy rather than the defect concentration plays a decisive role in the Sb2(S,Se)3 photovoltaic performance. Admittance spectroscopy analysis is used to obtain efficient Sb2(S,Se)3 solar cells. By employing dual‐source coordinations to optimize the absorber layer a power conversion efficiency of 8.17% is obtained which is the highest efficiency for Sb2(S,Se)3 solar cells fabricated by vapor transport technology. This study suggests that there are other opportunities for gaining deeper a understanding of the defect physics and carrier recombination mechanisms in other highly oriented low‐dimensional materials to achieve improved device performance.
Despite
many successful realizations of laser operations in various
micro/nanostructured lead halide perovskites (LHPs), the electron–hole
plasma (EHP) lasing dynamics has only rarely been reported, especially
for wide-gap Cl-rich perovskites. In this work, the temporal lasing
dynamics of whispering gallery mode (WGM) CsPbCl
m
Br3–m
microplate lasers
are systematically investigated, for the first time, with a streak
camera system. As the pump fluence increases, the gain profile exhibits
a monotonous redshift, indicating the EHP lasing in the microplate
cavity, while an opposite shift of the gain region is observed with
time decay due to the gradual depletion of carriers. This directly
reflects the change of the bandgap renormalization effect at varying
pump fluences. Additionally, the individual lasing modes present identifiable
blueshifts with elevated pump levels and redshifts with time delay,
which can be unraveled by the carrier-induced refractive index change
in the LHP cavity. Moreover, the wavelength-dependent lasing duration
demonstrates that lasing in the EHP regime depends not only on the
carrier density, but also on the bandgap variation with carrier density.
By directly modulating the pump fluence, the onset delay of the microlaser
can be efficiently tuned. Our results provide a comprehensive understanding
of the EHP lasing mechanism and carrier dynamics in the WGM LHP micro/nanolasers
and will push their technological relevance in integrated photonics.
In this paper, we demonstrate numerical evidence that interfacial passivation in the Sb 2 Se 3 solar cell forming the configuration of indium tin oxide (ITO)/SnO 2 /CdS/Sb 2 Se 3 /Au is beneficial for suppressing defects and obtaining cells with high efficiency. First, the effects of two types of defects including bulk defects in the Sb 2 Se 3 absorber layer and interfacial defects at the CdS/Sb 2 Se 3 interface on the performance of solar cells are studied, respectively. It is found that the effect of the bulk defects varied greatly in different magnitudes of defect density, whereas significant deterioration could be caused by the interfacial defect at relatively lower defect density. Then, the types of three actual defects named D1, D2, and D3 measured experimentally in the Sb 2 Se 3 solar cells are analyzed by comparing the simulation and experimental results. It is found that the case D1 and D2 existing in the absorber layer while D3 located at the interface makes the simulation and experimental results the most consistent, in which the interfacial defect D3 contributes the most to the degradation of cell performance. Finally, a SnO 2 -free Sb 2 Se 3 solar cell sample is simulated to evaluate the crucial interfacial passivation effect of the SnO 2 layer. The results show that introducing a SnO 2 layer is beneficial for the passivation of not only the interfacial defects but some unclear mechanisms such as deep-level defects which are hard to be measured in the present experiment. The numerical simulation results provide evidence proving the importance of interfacial passivation in actual fabrication processes to improve the performance of Sb 2 Se 3 solar cells.
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