Extended carrier lifetimes and diffusion in hybrid perovskites revealed by Hall effect and photoconductivity measurements

Abstract

Impressive performance of hybrid perovskite solar cells reported in recent years still awaits a comprehensive understanding of its microscopic origins. In this work, the intrinsic Hall mobility and photocarrier recombination coefficient are directly measured in these materials in steady-state transport studies. The results show that electron-hole recombination and carrier trapping rates in hybrid perovskites are very low. The bimolecular recombination coefficient (10−11 to 10−10 cm3 s−1) is found to be on par with that in the best direct-band inorganic semiconductors, even though the intrinsic Hall mobility in hybrid perovskites is considerably lower (up to 60 cm2 V−1 s−1). Measured here, steady-state carrier lifetimes (of up to 3 ms) and diffusion lengths (as long as 650 μm) are significantly longer than those in high-purity crystalline inorganic semiconductors. We suggest that these experimental findings are consistent with the polaronic nature of charge carriers, resulting from an interaction of charges with methylammonium dipoles.

Origin of long lifetime of band-edge charge carriers in organic–inorganic lead iodide perovskites

“…It is because, even if ferroelectric domains are formed in the lower symmetry phases at lower temperatures (8,37), such domains are expected to disappear in the high-symmetry cubic phase (37). Among other mechanisms that have been proposed to explain the long lifetime, our results support the scenario of formation of large polarons, which is consistent with the long carrier lifetime but modest carrier mobilities observed in HOIPs (14)(15)(16). Such screening phenomena are not rare.…”

“…The most dominant contribution to the high photovoltaic performance of HOIPs comes from their long carrier lifetimes (≥ 1 μs), which translates to large carrier diffusion lengths despite their modest charge mobilities (5). Several microscopic mechanisms behind the unusually long carrier lifetime have been proposed, such as formation of ferroelectric domains (6)(7)(8)(9), Rashba effect (10)(11)(12), photon recycling (13), and large polarons (14)(15)(16). When the HOIPs are replaced with all inorganic perovskites in the solar cell architecture, the device can still function as a solar cell.…”

“…Third, it was proposed that large polarons are formed by organic cations when they reorient themselves in response to the presence of photoexcited electrons and holes (14)(15)(16). As a result, the screened carriers are protected from scattering by defects and phonons, leading to the prolonged lifetime.…”

Strong Exciton–Photon Coupling in Hybrid Inorganic–Organic Perovskite Micro/Nanowires

“…Hybrid inorganic-organic halide perovskite materials have attracted intensive attention due to their superior characteristics, such as high absorption coefficient, [1,2] long carriers diffusion length, [3,4] tunable band gap, [5,6] and low trap density, [7,8] which make them suitable for important optoelectronic devices, including high-efficient solar cells, [9,10] photodetectors, [11][12][13] light emission diodes (LEDs), [14][15][16] and lasers. [17,18] Perovskite thin film based solar cells have reached a In recent several years, high quality perovskite micro/nanowires, which are serving as miniaturized fundamental building blocks for nanoscale optoelectronic devices, have been widely studied as typical optical cavities in small lasers.…”

Crystallographically Aligned Perovskite Structures for High‐Performance Polarization‐Sensitive Photodetectors

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Single-crystalline halide perovskites, such as organic-inorganic hybrid CH 3 NH 3 PbX 3 and all-inorganic CsPbX 3 (X = Cl, Br, I), possess remarkable optoelectronic properties of long, balanced carrier diffusion length, high absorption coefficient, low trap density, and excellent mobility, thus affording their widespread applications to efficient solar cells and high-gain photodetectors. [11][12][13][14][15] For example, Huang and co-workers have demonstrated strong surface-charge recombination on singlecrystalline perovskite, which have lead to photodetectors with a narrowband response. [11][12][13][14][15] For example, Huang and co-workers have demonstrated strong surface-charge recombination on singlecrystalline perovskite, which have lead to photodetectors with a narrowband response.

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