Revealing lattice and photocarrier dynamics of high-quality MAPbBr3 single crystals by far infrared reflection and surface photovoltage spectroscopy

Abstract

Hybrid organic-inorganic lead halide perovskite materials show great promise in a number of optoelectronic applications, including solar cells, light emitting diodes, and photodetectors. Understanding their intrinsic material properties is critical to enhancing device performance and enabling innovative material and device designs. Here, we study lattice dynamics using far-infrared (FIR) reflectance and photogenerated carrier dynamics using surface photovoltage (SPV) measurements on high-quality methylammonium lead bromide (MAPbBr3) single crystals. FIR reflectance shows three coherent infrared-active phonon modes between 40 and 200 cm−1 that result in reststrahlen bands with much higher peak reflectance than has been previously reported. The phonon mode strength and damping are comparable to classical oxide perovskite single crystals. However, the effects of defects on photogenerated carrier recombination are still evident in SPV measurements. By performing SPV over different spectral ranges, we are able to separate the effects of surface and bulk defects on the recombination dynamics of photogenerated charge carriers. We further apply SPV measurements to obtain the minority carrier (electron) diffusion length for the MAPbBr3 crystal. This study demonstrates that both FIR reflectance and SPV measurements provide useful information on the electromagnetic response properties of halide perovskite single crystals.

Bismuth Doping Alters Structural Phase Transitions in Methylammonium Lead Tribromide Single Crystals

“…Previous studies on undoped crystals have similarly correlated increases in the (002)/(001) intensity ratio with increasing long-range disorder, as verified by far-infrared reflection (FIR) spectroscopy. 28 More ordered MAPbBr 3 crystals, those with fewer stacking faults or dislocations as quantified by a higher farinfrared reflectance intensity, also exhibit higher (001) diffraction peak intensities with respect to their (002) planes. This result is also consistent with the optical microscopy images (Figure S1), where we clearly resolve hillock-like crystalline growth fronts in the undoped crystal.…”

Solid-State Neutron Detection Based on Methylammonium Lead Bromide Perovskite Single Crystals

“…Note that a freshly mixed precursor solution is used for every growth cycle. The grown MAPbBr 3 single crystals used to fabricate the diodes in this study were previously optimized and characterized in Wang et al to verify the crystal properties …”

“…The grown MAPbBr 3 single crystals used to fabricate the diodes in this study were previously optimized and characterized in Wang et al to verify the crystal properties. 47 4.2. Chemical, Structural, Electrical, and Radiation Characterization.…”

Synthesis and Investigation of the Properties of Organic-Inorganic Perovskite Films with Non-Contact Methods

“…Therefore, the Goodman approach has used by Dittrich [15] cannot, in principle, to give the exact diffusion length for minority charge carriers in perovskite films with a relief surface. Weng [16] also applied the Goodman surface photovoltage spectroscopy method to determine the diffusion length of minority charge carriers in CH 3 NH 3 PbBr 3 crystals. In their measurements, all the criteria of the method were met, except the small signal: the surface photovoltage values were SPV = 70-200 mV, which is 3-4 times higher than / , but not vice versa.…”

“…Thus, there are no grounds for claiming the accurate measurement of the diffusion length. We can only talk about rough estimates of its value obtained in those works [16]. In the present work, it is proposed to use the method of spectrally resolved small-signal surface photovoltage together with the measurements of the optical properties (transmission and reflection) for the characterization and development of fabrication technologies of perovskite films with different microstructures.…”