Increased Throughput and Sensitivity of Synchrotron-Based Characterization for Photovoltaic Materials

Morishige, Ashley E.; Laine, Hannu S.; Looney, Erin E.; Jensen, Mallory A.; Vogt, Stefan; Li, Joel B.; Lai, Barry; Savin, Hele; Buonassisi, Tonio

doi:10.1109/jphotov.2017.2681199

Cited by 10 publications

(5 citation statements)

References 40 publications

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“…Given that the signal-tonoise ratio in XBIC measurements is rather limited by currents induced by the environment than by statistics, the integration time can be even below 1 ms if the response chain of the solar cell/amplifier/data acquisition system is fast enough. However, the scanning speed may be limiting, in particular if no continuous "fly scan mode" 35 or fast shutter is available, such that the sample degrades during the settling time prior to the measurement at each scan position. In this case, the scan step size may be increased to match the diameter of the interaction volume that ultimately limits the spatial resolution and can be larger than the probe diameter at X-ray nano-and microprobe endstations.…”

Section: ■ Resultsmentioning

confidence: 99%

Effects of X-rays on Perovskite Solar Cells

et al. 2020

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Synchrotron micro-and nanoprobe beamlines have demonstrated great potential to advance photovoltaic devices. Most importantly, their small X-ray spotsize has enabled the direct correlation of electrical performance with elemental composition at sub-grain resolution for a variety of polycrystalline solar cells. Whereas the bulk of most inorganic semiconductors is stable under the high X-ray flux of focused Xray beams, semiconductors with organic components are prone to a variety of degradation mechanisms. This is particularly critical to evaluate for the emerging organometal halide perovskite solar cells. Here, we investigate the effects of hard X-rays on the nanoscale per-degradation-induced measurement artifacts can be outrun and showcase the high correlation of the X-ray beam induced current with the iodine and lead distribution.

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Section: ■ Resultsmentioning

confidence: 99%

Effects of X-rays on Perovskite Solar Cells

et al. 2020

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“…Synchrotron-based X-ray fluorescence microscopy was performed at beamline 2-ID-D at the Advanced Photon Source, Argonne National Laboratory, at an excitation energy of 9 keV with a 200 nm spot size, step sizes of 500 nm (1000 ppm film) and 220 nm (1 at.% film), and dwell times of 20 ms (1000 ppm film) and 25 ms (1 at.% film), which were enabled by on-the-fly data collection mode . No chemical or structural changes to the films from the beam were observed.…”

Section: Experimental Methodsmentioning

confidence: 99%

High Tolerance to Iron Contamination in Lead Halide Perovskite Solar Cells

et al. 2017

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The relationship between charge-carrier lifetime and the tolerance of lead halide perovskite (LHP) solar cells to intrinsic point defects has drawn much attention by helping to explain rapid improvements in device efficiencies. However, little is known about how charge-carrier lifetime and solar cell performance in LHPs are affected by extrinsic defects (i.e., impurities), including those that are common in manufacturing environments and known to introduce deep levels in other semiconductors. Here, we evaluate the tolerance of LHP solar cells to iron introduced via intentional contamination of the feedstock and examine the root causes of the resulting efficiency losses. We find that comparable efficiency losses occur in LHPs at feedstock iron concentrations approximately 100 times higher than those in p-type silicon devices. Photoluminescence measurements correlate iron concentration with nonradiative recombination, which we attribute to the presence of deep-level iron interstitials, as calculated from first-principles, as well as iron-rich particles detected by synchrotron-based X-ray fluorescence microscopy. At moderate contamination levels, we witness prominent recovery of device efficiencies to near-baseline values after biasing at 1.4 V for 60 s in the dark. We theorize that this temporary effect arises from improved charge-carrier collection enhanced by electric fields strengthened from ion migration toward interfaces. Our results demonstrate that extrinsic defect tolerance contributes to high efficiencies in LHP solar cells, which inspires further investigation into potential large-scale manufacturing cost savings as well as the degree of overlap between intrinsic and extrinsic defect tolerance in LHPs and "perovskite-inspired" lead-free stable alternatives.

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“…We first perform an “electronic” measurement map, followed by an “elemental” map. For the electronic map, we combine high‐throughput fly‐scanning mapping that reduces scanning time to a typical 20–50 ms per point dwell time and insert beam attenuation filters to reduce X‐ray dose. This strategy takes advantage of the ≈10 3 multiplication factor of band edge electrons generated per single hard X‐ray photon and the relative ease of low‐noise amplification of pA current measurements.…”

Section: Tools To Assess Nanoscale Perovskite Chemistry and Its Optoementioning

confidence: 99%

The Relationship between Chemical Flexibility and Nanoscale Charge Collection in Hybrid Halide Perovskites

Luo

Aharon

Stückelberger

et al. 2018

Adv Funct Materials

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Hybrid organometal halide perovskites are known for their excellent optoelectronic functionality as well as their wide-ranging chemical flexibility. The composition of hybrid perovskite devices has trended toward increasing complexity as fine-tuned properties are pursued, including multielement mixing on the constituents A and B and halide sites. However, this tunability presents potential challenges for charge extraction in functional devices. Poor consistency and repeatability between devices may arise due to variations in composition and microstructure. Within a single device, spatial heterogeneity in composition and phase segregation may limit the device from achieving its performance potential. This review details how the nanoscale elemental distribution and charge collection in hybrid perovskite materials evolve as chemical complexity increases, highlighting recent results using nondestructive operando synchrotron-based X-ray nanoprobe techniques. The results reveal a strong link between local chemistry and charge collection that must be controlled to develop robust, high-performance hybrid perovskite materials for optoelectronic devices.applications including solar cells, [1,2] lightemitting diodes, [3] lasers, [4] and photodetectors. [5] The exceptional minority carrier diffusion lengths in these materials [6,7] lead to nearly 100% internal quantum efficiency [8] which results in high charge-carrier collection efficiency and high external luminescence efficiency in electron-photon conversion devices. [9] Particularly in the field of photovoltaics (PV), their extraordinary material properties [10][11][12] have enabled perovskite solar absorbers to achieve large improvements in device performance in the past 8 years. The perovskite crystal structure is shown in Figure 1a, where the A-site is CH 3 NH 3 + (MA, methylammonium), the B-site is Pb 2+ , and the X-site is I − following the general perovskite formula ABX 3. After demonstration of a device with 3.8% power conversion efficiency (PCE) by Miyasaka and co-workers in a dye-sensitized solar cell architecture using CH 3 NH 3 PbI 3 , [13] a breakthrough in perovskite photovoltaics occurred in 2012 when the first allsolid-state hybrid perovskite devices were shown by Kim et al., [14] improving the chemical stability of the perovskite and enabling device performance to exceed beyond 9% using CH 3 NH 3 PbI 3 perovskites. With intense investigation of perovskite material properties from research groups all over the world, including bandgap engineering by halide mixing [15,16] and device optimization using A-site mixing, [9,17] the record PCE of hybrid perovskite solar cells reached 22.7% in 2017 after achieving 22.1% PCE in 2015 [18] using a mixture of formamidinium lead iodide (CH(NH 2 ) 2 PbI 3 ) with 5% loading of methylammonium lead bromide (CH 3 NH 3 PbBr 3 ) chemistry. [19,20] Surpassing 22% PCE by leveraging the chemical flexibility of the perovskite structure brought hybrid perovskite solar cells on par in efficiency with most polycrystalline solar absor...

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Increased Throughput and Sensitivity of Synchrotron-Based Characterization for Photovoltaic Materials

Cited by 10 publications

References 40 publications

Effects of X-rays on Perovskite Solar Cells

Effects of X-rays on Perovskite Solar Cells

High Tolerance to Iron Contamination in Lead Halide Perovskite Solar Cells

The Relationship between Chemical Flexibility and Nanoscale Charge Collection in Hybrid Halide Perovskites

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