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Nanoscale heterogeneity of ultrafast many-body carrier dynamics in triple cation perovskites
In high fluence applications of lead halide perovskites for light-emitting diodes and lasers, multi-polaron interactions and associated Auger recombination limit the device performance. However, the relationship of the ultrafast and strongly lattice coupled carrier dynamics to nanoscale heterogeneities has remained elusive. Here, in ultrafast visible-pump infrared-probe nano-imaging of the photoinduced carrier dynamics in triple cation perovskite films, a ~20 % variation in sub-ns relaxation dynamics with spatial disorder on tens to hundreds of nanometer is resolved. We attribute the non-uniform relaxation dynamics to the heterogeneous evolution of polaron delocalization and increasing scattering time. The initial high-density excitation results in faster relaxation due to strong many-body interactions, followed by extended carrier lifetimes at lower densities. These results point towards the missing link between the optoelectronic heterogeneity and associated carrier dynamics to guide synthesis and device engineering for improved perovskites device performance.
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Adding Spin Functionality to Traditional Optoelectronics via Chiral Perovskite
Spin polarized current generation and injection into semiconductors at room
temperature are key to enable a broader range of opto-spintronic
functionalities, yet the inherent efficiency of spin injection across commonly
used semiconductor-ferromagnet interfaces is limited. Here, we demonstrate
efficient spin injection into commercially viable III-V light emitting diodes
(LED) by integrating chiral halide perovskite layers with (AlxGa1-x)0.5In0.5P
multiple quantum wells (MQW). Spin polarized current is injected via chirality
induced spin selectivity (CISS) and the spin accumulation in the III-V
semiconductor is detected via the emission of circularly polarized light with a
degree of circular polarization of up to ~ 15%. X-ray photoemission
spectroscopy (XPS) and transmission electron microscopy (TEM) cross sectional
imaging indicate a pristine perovskite/III-V interface. These findings
demonstrate chiral perovskite semiconductors transform well-developed
semiconductor platforms to enable control over spin, charge, and light