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We present experimental evidence showing that the effective carrier diffusion length ($L_d$) and lifetime ($\tau$) depend on the carrier density in MAPbBr$_3$ single crystals. Independent measurements reveal that both $L_d$ and $\tau$ decrease with an increase in photo-carrier density. Scanning photocurrent microscopy is used to extract the characteristic photocurrent $I_{ph}$ decay-length parameter, $L_d$, which is a measure of effective carrier diffusion. The $L_d$ magnitudes for electrons and holes were determined to be ~ 13.3 $\mu$m and ~ 13.8 $\mu$m respectively. A marginal increase in uniform light bias ($\leq 5 \times 10^{15}$ photons/cm$^2$) increases the modulated photocurrent magnitude and reduces the $L_d$ parameter by a factor of two and three for electrons and holes respectively, indicating that the recombination is not monomolecular. The $L_d$ variations were correlated to the features in photoluminescence lifetime studies. Analysis of lifetime variation shows intensity-dependent monomolecular and bimolecular recombination trends with recombination constants determined to be ~ 9.3 $\times 10^6$ s$^{-1}$ and ~ 1.4 $\times 10^{-9}$ cm$^{3}$s$^{-1}$ respectively. Based on the trends of $L_d$ and lifetime, it is inferred that the sub-band-gap trap recombination influences carrier transport in the low-intensity excitation regime, while bimolecular recombination and transport dominate at high intensity., Comment: 19 pages, 6 figures

State-of-the-art Li (or Na) ion batteries work by insertion/extraction of the alkali metal ions into a porous electrode material, where the overall capacity is strongly dependent on the accessibility of the host material interior to the ions. On the other hand, the performance stability depends on various factors governed by the specific constitution of the electrode. Here we show that molecularly engineered low-dimensional hybrid perovskites can work as excellent anode materials for alkali-ion batteries. We measure a high reversible capacity of 646 mA h g−1 at 100 mA g−1 with good stability tested up to 250 cycles for the benzidine mediated lead iodide based 1D system. An ex situ analysis of the electrodes reveals that the storage primarily occurs via the Lix(or Nax)Pb alloying/de-alloying process. We anticipate that these results open a new direction for the use of low-dimensional hybrid perovskites for energy storage applications.

This review aims to capture the emergent scenario of research in the field of organic–inorganic hybrid perovskites and inorganic halide perovskites as fuelled by the continuing excitement about these materials, their unique properties and their immense application potential in photovoltaics and optoelectronics. While some spectacular successes have already been achieved in respect of these applications, several challenges have also been encountered in terms of the stability of these materials under different ambients and stimuli, and their integration with other functional materials to generate new device architectures. Towards this end, this review discusses pertinent strategies to tune and control their device-worthy properties and eliminate their shortcomings to the extent feasible. These include (a) intelligent doping in these structurally and chemically sensitive systems, (b) the role of defects and strategies to mitigate them via innovative synthetic controls, (c) molecular engineering to control the dimensionality and new phases in these materials, and (d) the emergent understanding about the structure–chemistry–property relationships, especially the photophysical properties. We also address the bearing that these issues have on the ultimate realisation of robust high-efficiency solar cells, either in stand-alone or tandem configurations, as well as on high-performance light-emitting diodes. The insights gained by first-principles density functional theory calculations to understand the experimental observations and to predict new material designs are also discussed. The review is concluded with a section on the summary and outlook, wherein the authors’ perspective on the emergent scenario is presented.

The present solid state lighting (SSL) technology is based on using a combination of phosphors to give the desired white light emitting devices. The property of broadband emission from a single pho ...

Significant enhancement in the luminescence and superior photophysical properties of CH3NH3PbBr3 thin films prepared via simple single step spin coating process involving a novel additive mediated solvent extraction step is reported. This process results in significantly lower disorder in CH3NH3PbBr3 perovskites with Urbach energies reducing from ≈35 to ≈17 meV, which is the lowest reported value to date. The additive mediated process also results in a remarkable improvement in the photoluminescence quantum yields (PLQYs) from 1% to 30%. Coupled with the overall increase in surface roughness, a significant increase in the internal PLQY from 7% to 77% is estimated, indicating the superior quality of the treated thin films. The resultant high quality CH3NH3PbBr3 perovskites with remarkable photophysical properties can be used in realizing highly efficient optoelectronic devices. Highly efficient light emitting diodes using these perovskites are demonstrated here.