Single-Particle Organolead Halide Perovskite Photoluminescence as a Probe for Surface Reaction Kinetics

Abstract

Photoluminescence (PL) of organolead halide perovskites (OHPs) is sensitive to OHPs’ surface conditions and is an effective way to report surface states. Literature has reported that at the ensemble level, the PL of photoexcited OHP nanorods declines under an inert nitrogen (N2) atmosphere and recovers under subsequent exposure to oxygen (O2). At the single-particle level, we observed that OHP nanorods photoblink at rates dependent on both the excitation intensity and the O2 concentration. Combining the two sets of information with the charge-trapping/detrapping mechanism, we are able to quantitatively evaluate the interaction between a single surface defect and a single O2 molecule using a new kinetic model. The model predicts that the photodarkening of OHP nanorods in the N2 atmosphere has a different mechanism than conventional PL quenching, which we call photo-knockout. This model provides fundamental insights into the interactions of molecular O2 with OHP materials and helps design a suitable OHP interface for a variety of applications in photovoltaics and optoelectronics.

Environment‐Dependent Metastable Nonradiative Recombination Centers in Perovskites Revealed by Photoluminescence Blinking

“…Notably, the PL properties of OMHP materials are sensitive to changing atmosphere. [7][8][9][10][11] Exposing OMHPs to oxygen (O 2 ) has been reported to enhance PL under light illumination, whereas immersion in inner nitrogen (N 2 ) results in a PL decline. [7,8] The light-curing effect in O 2 suggests annihilation of nonradiative decay pathways by molecular O 2.…”

“…Therefore, PL blinking of perovskite nano-or microparticles provides us a powerful tool to study the metastable nonradiative recombination centers. Recently, several experiments based on single-molecule spectroscopy were conducted to investigate the fundamental mechanism in perovskite PL blinking, either by changing temperature [24] or by immersing the sample with different atmospheric environments [9][10][11] and encapsulation polymers. [25] Herein, we use PL blinking of individual MAPbI 3 crystals as an indicator of the number and efficiency of individual nonradiative recombination centers in the crystals.…”

Phase Segregation and Photothermal Remixing of Mixed-Halide Lead Perovskites

“…13,33,36 In this report, we track the phase segregation of methylammonium lead halide MHP films (CH3NH3Pb(BrxI1-x)3) over space and time using a home-built PL emission micro-spectroscope. 37 Briefly, the films are illuminated under a wide-field fluorescence microscope (supporting information, SI Figure S1). A slit and a transmission grating are inserted before the EMCCD camera.…”

Stochastic Adsorption of Diluted Solute Molecules at Interfaces

“…For example, we have fitted kinetic data using our home-made code jcfit (Github) to optimizing simulations for a given set of data. 40,43 For the back-diffusion term, I am curious about simulating a routing experiment I have done before, self-assembly of alkanethiol molecules on gold or ZnO surface, 44 particularly in how long it takes to reach a whole surface coverage with no convection and stirring. Thus I simulate the adsorption kinetics of octadecanethiol in ethanol (concentration from 10 μM to 1 mM) on a flat surface assuming the adsorption probability in binary using the Metropolis Monte Carlo Method.…”