Halide Perovskite Single Crystals and Nanocrystal Films as Electron Donor‐Acceptor Heterojunctions

Abstract

Halide perovskites are materials for future optical displays and solar cells. Electron donor-acceptor perovskite heterostructures with distinguishing halide compositions are promising for transporting and harvesting photogenerated charge carriers. Combined ebeam lithography and anion exchange are promising to develop such heterostructures but challenging to prepare multiple heterojunctions at desired locations in single crystals. We demonstrate swift laser trappingassisted band gap engineering at the desired locations in MAPbBr 3 microrods, microplates, or nanocrystal thin films. The built-in donor-acceptor double and multiheterojunction structures let us transport and trap photogenerated charge carriers from wide-band gap bromide to narrow-band gap iodide domains. We discuss the charge carrier transport and trapping mechanisms from the viewpoints of engineered bands and band continuity. This work offers a convenient method for designing single-, double-and multi-heterojunction donor-acceptor halide perovskites for photovoltaic, photonic, and electronic applications.

Growth and High-Performance Photodetectors of CsPbBr3Single Crystals

“…The growth of perovskite microcrystals is usually obtained using solvent volatilization, which produces single crystals of micron size. Using this method, it is difficult to grow large single crystals of high quality and tends to lead to polycrystallization. − The development of techniques for the growth of large single crystals of perovskite is warranted. The experimental growth of large perovskite single crystals using the inverse temperature method is very simple.…”

Excitation Laser Power and Temperature-Dependent Luminescence of Optically Trapped Upconversion Particles

“…For an upconversion particle, a Gaussian beam exerts a gradient force from the periphery toward the center of the beam. Suppose the radially symmetric gradient force is strong enough to compensate for the scattering force (due to radiation pressure) along the beam propagation direction; in that case, the microparticle will be optically arrested in all three dimensions. , …”

“…Suppose the radially symmetric gradient force is strong enough to compensate for the scattering force (due to radiation pressure) along the beam propagation direction; in that case, the microparticle will be optically arrested in all three dimensions. 54,55 To excite the optically trapped upconversion particle for the fluorescence measurements, radiation from a 980 nm laser is coupled through the same 100× objective by using a dichroic mirror (DM1). The 980 nm laser is employed here for fluorescence emission as the excitation wavelength matches with the electronic transition levels of Yb 3+ so that a higher quantum yield can be achieved.…”

Crystallization Retardation and Synergistic Trap Passivation in Perovskite Solar Cells Incorporated with Magnesium-Decorated Graphene Quantum Dots

“…Photovoltaic devices have been developed as a renewable, clean energy technology to tackle serious global warming environmental issues . Perovskite solar cells (PSCs) are the most encouraging emerging PV technology because of their low cost, , simple solution processing, high optical absorption coefficients over the solar spectrum, tunable bandgap, low exciton binding energies, long-range carrier diffusion, and high defect tolerance . Organic–inorganic hybrid PSCs have made rapid progress, where the power conversion efficiency (PCE) has advanced drastically from 3.8 to 25.7% , in the past decade.…”