Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites

Doherty, Tiarnan A. S.; Winchester, Andrew; Macpherson, Stuart; Johnstone, Duncan N.; Pareek, Vivek; Tennyson, Elizabeth M.; Kosar, Sofiia; Kosasih, Felix Utama; Anaya, Miguel; Abdi-Jalebi, Mojtaba; Andaji‐Garmaroudi, Zahra; Wong, E Laine; Madéo, Julien; Chiang, Yu‐Hsien; Park, Ji-Sang; Jung, Young-Kwang; Petoukhoff, Christopher E.; Divitini, Giorgio; Man, Michael K. L.; Ducati, Caterina; Walsh, Aron; Midgley, Paul A.; Dani, Keshav M.; Stranks, Samuel D.

doi:10.1038/s41586-020-2184-1

Cited by 298 publications

(348 citation statements)

References 52 publications

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“…To investigate the density of occupied states at and above the VBM of MAPbI 3 and other MHP films, we use ultraviolet photoemission spectroscopy (UPS), which has been previously utilized to detect the presence of occupied gap states in organic [13,14] and MHPs. [15][16][17][18][19] A range of other techniques have been used in past years to investigate gap states in MHPs, for example optical photoluminescence and electrical (space charge limited current, SCLC) measurements, [20] Hall effect measurements, [21] microwave conductivity, [22] or impedance spectroscopy. [23] Yet, photoemission, and UPS in particular, remains one of the techniques that provides the most direct visualization of the density of states extending into the gap above the VBM.…”

Section: Understanding the Origin And Distribution Of Electronic Gapmentioning

confidence: 99%

Gap States in Methylammonium Lead Halides: The Link to Dimethylsulfoxide?

et al. 2020

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Understanding the origin and distribution of electronic gap states in metal halide perovskite (MHP) thin films is crucial to the further improvement of the efficiency and long‐term stability of MHP‐based optoelectronic devices. In this work, the impact of Lewis‐basic additives introduced in the precursor solution on the density of states in the perovskite bandgap is investigated. Ultraviolet photoemission spectroscopy and contact potential difference measurements are conducted on MHP thin films processed from dimethylformamide (DMF)‐based solutions to which either no additive, dimethylsulfoxide (DMSO), or N‐methylpyrrolidine‐2‐thione (NMPT) is added. The results show the presence of a density of states in the gap of methylammonium lead halide films processed from DMSO‐containing solution. The density of gap states is either suppressed when the methylammonium concentration in mixed cation films is reduced or when NMPT is used as an additive, and eliminated when methylammonium (MA) is replaced with cesium or formamidinium (FA). These results are consistent with the notion that reaction products that result from DMSO reacting with MA+ in the precursor solution are responsible for the formation of gap states.

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Section: Understanding the Origin And Distribution Of Electronic Gapmentioning

confidence: 99%

Gap States in Methylammonium Lead Halides: The Link to Dimethylsulfoxide?

et al. 2020

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“…SED has recently been applied to characterize correlated defects, for example, using the symmetry within individual convergent beam diffraction disks to map domains in relaxor ferroelectrics, 33 superlattice reflections as signatures of correlated disorder in meteorites, 34 and dark-field imaging to resolve monoclinic variants in transition metal oxides. 35 Further, SED has been applied to beam sensitive materials revealing crystallinity in organic molecular crystals, 36 polymers, 37 halide perovskites, 38 and MOFs. 39 , 40 Here, we apply SED to directly visualize nanoscale defect domains in UiO-66(Hf).…”

Section: Introductionmentioning

confidence: 99%

Direct Imaging of Correlated Defect Nanodomains in a Metal–Organic Framework

et al. 2020

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Defect engineering can enhance key properties of metal–organic frameworks (MOFs). Tailoring the distribution of defects, for example in correlated nanodomains, requires characterization across length scales. However, a critical nanoscale characterization gap has emerged between the bulk diffraction techniques used to detect defect nanodomains and the subnanometer imaging used to observe individual defects. Here, we demonstrate that the emerging technique of scanning electron diffraction (SED) can bridge this gap uniquely enabling both nanoscale crystallographic analysis and the low-dose formation of multiple diffraction contrast images for defect analysis in MOFs. We directly image defect nanodomains in the MOF UiO-66(Hf) over an area of ca. 1000 nm and with a spatial resolution ca. 5 nm to reveal domain morphology and distribution. Based on these observations, we suggest possible crystal growth processes underpinning synthetic control of defect nanodomains. We also identify likely dislocations and small angle grain boundaries, illustrating that SED could be a key technique in developing the potential for engineering the distribution of defects, or “microstructure”, in functional MOF design.

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“…An adequate synergy between theoretical and experimental studies is crucial toward the development of a new generation of novel, efficient materials for widespread use (Stevanović et al, 2014 ; Sachs et al, 2018 ; Wang et al, 2019 ; Davies et al, 2020 ; Doherty et al, 2020 ). A set of qualitative measures should include an evaluation of how experimental analysis influence on the effective development of an underlying theory and to define the limitations and constrictions bound to first-principle calculations.…”

Section: Qualitative Approaches For the Assessment Of Photocatalyticmentioning

confidence: 99%

Qualitative Approaches Towards Useful Photocatalytic Materials

Quesada-Cabrera

Parkin

2020

Front. Chem.

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The long-standing crusade searching for efficient photocatalytic materials has resulted in a vast landscape of promising photocatalysts, as reflected by the number of reviews reported in the last decade. Virtually all of these reviews have focused on quantitative approaches aiming at developing an understanding of the underlying mechanisms behind photocatalytic behavior and the parameters that influence structure-function correlation. Less attention has been paid, however, to qualitative measures around the development and assessment of photocatalysts. These measures will contribute toward narrowing the range of potential photocatalytic materials for widespread applications. The current report provides a critical perspective over some of the main factors affecting the assessment of photocatalytic materials as a code of good practice. A case of study is also provided, where this qualitative analysis is applied to one of the most prolific materials of the last-decade, disorder-engineered, black titanium dioxide (TiO 2).

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Performance-limiting nanoscale trap clusters at grain junctions in halide perovskites

Cited by 298 publications

References 52 publications

Gap States in Methylammonium Lead Halides: The Link to Dimethylsulfoxide?

Gap States in Methylammonium Lead Halides: The Link to Dimethylsulfoxide?

Direct Imaging of Correlated Defect Nanodomains in a Metal–Organic Framework

Qualitative Approaches Towards Useful Photocatalytic Materials

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