Title: Countdown to perovskite space lunch: Guidelines to performing relevant radiation-hardness experiments
Perovskite photovoltaics (PVs) are under intensive development for promise in terrestrial energy production. Soon, the community will find out how much of that promise may become reality. Perovskites also open new opportunities for lower cost space power. However, radiation tolerance of space environments requires appropriate analysis of relevant devices irradiated under representative radiation conditions. We present guidelines designed to rigorously test the radiation tolerance of perovskite PVs. We review radiation conditions in common orbits, calculate nonionizing and ionizing energy losses (NIEL and IEL) for perovskites, and prioritize proton radiation for effective nuclear interactions. Low-energy protons (0.05–0.15 MeV) create a representative uniform damage profile, whereas higher energy protons (commonly used in ground-based evaluation) require significantly higher fluence to accumulate the equivalent displacement damage dose due to lower scattering probability. Furthermore, high-energy protons may ‘‘heal’’ devices through increased electronic ionization. These procedural guidelines differ from those used to test conventional semiconductors. more »« less
Kirmani, Ahmad R.; Byers, Todd A.; Ni, Zhenyi; VanSant, Kaitlyn; Saini, Darshpreet K.; Scheidt, Rebecca; Zheng, Xiaopeng; Kum, Tatchen Buh; Sellers, Ian R.; McMillon-Brown, Lyndsey; et al
(, Nature Communications)
Natalie Lok Kwan Li, PhD
(Ed.)
Perovskite photovoltaics have been shown to recover, or heal, after radiation damage. Here, we deconvolve the effects of radiation based on different energy loss mechanisms from incident protons which induce defects or can promote efficiency recovery. We design a dual dose experiment first exposing devices to low-energy protons efficient in creating atomic displacements. Devices are then irradiated with high-energy protons that interact differently. Correlated with modeling, high-energy protons (with increased ionizing energy loss component) effectively anneal the initial radiation damage, and recover the device efficiency, thus directly detailing the different interactions of irradiation. We relate these differences to the energy loss (ionization or non-ionization) using simulation. Dual dose experiments provide insight into understanding the radiation response of perovskite solar cells and highlight that radiation-matter interactions in soft lattice materials are distinct from conventional semiconductors. These results present electronic ionization as a unique handle to remedying defects and trap states in perovskites.
Sharma, Mohin; Parashar, Mritunjaya; Saini, Darshpreet Kaur; Byers, Todd A; Bowen, Charles; Khanal, Megh N; Whiteside, Vincent R; Kirmani, Ahmad R; Luther, Joseph M; Sellers, Ian R; et al
(, IEEE)
This paper discusses the in-situ characterization tools designed to assess radiation tolerance and elemental migration in perovskite materials. With the increasing use of perovskites in various technological applications, understanding their response to radiation exposure is paramount. Ion Beam Induced Charge (IBIC) emerges as a powerful tool for investigating the radiation tolerance of perovskites at the microscale. By employing focused ion beams, IBIC allows for the spatial mapping of charge carriers, offering insights into the material's electronic response to radiation-induced defects. This technique enables researchers to pinpoint areas of enhanced or suppressed charge collection, providing valuable information on the perovskite's intrinsic properties under irradiation. Rutherford Backscattering Spectrometry (RBS) complements the study by offering a quantitative analysis of elemental migration in perovskite materials. Through the precise measurement of backscattered ions, RBS provides a detailed understanding of the elemental composition and distribution within the perovskite lattice after radiation exposure. The integration of IBIC and RBS techniques in in-situ experiments enhances the comprehensive characterization of radiation effects on perovskites.
Cadmium telluride (CdTe) solar cells are a promising photovoltaic (PV) technology for producing power in space owing to their high-efficiency (> 22.1 %), potential for specific power, and cost-effective manufacturing processes. In contrast to traditional space PVs, the high-Z (atomic number) CdTe absorbers can be intrinsically robust under extreme space radiation, offering long-term stability. Despite these advantages, the performance assessment of CdTe solar cells under high-energy particle irradiation (e.g., photons, neutrons, charged particles) is limited in the literature, and their stability is not comprehensively studied. In this work, we present the PV response of n-CdS / p-CdTe PVs under accelerated neutron irradiation. We measure PV properties of the devices at different neutron/photon doses. The equivalent dose deposited in the CdTe samples is simulated with deterministic and Monte Carlo radiation transport methods. Thin-film CdTe solar cells were synthesized on a fluorine-doped tin oxide (FTO) coated glass substrate (≈ 4 cm × 4 cm). CdS:O (≈ 100 nm) was reactively RF sputtered in an oxygen/argon ambient followed by a close-spaced sublimation deposition of CdTe (≈ 3.5 μm) in an oxygen/helium ambient. The sample was exposed to a 10 min vapor CdCl2 in oxygen/helium ambient at 430˚C. The samples were exposed to a wet CuCl2 solution prior to anneal 200ºC. A gold back-contact was formed on CdTe via thermal evaporation. The final sample contains 16 CdTe devices. For neutron irradiation, we cleaved the CdTe substrate into four samples and exposed two samples to ≈ 90 kW reactor power neutron radiation for 5.5 hours and 8.2 hours, respectively, in our TRIGA (Training, Research, Isotopes, General Atomics) reactor. We observed a noticeable color change of the glass substrates to brown after the neutron/gamma reactor exposure. Presumably, the injected high-energy neutrons caused the breaking of chemical bonds and the displacement of atoms in the glass substrates, creating point defects and color centers. The I-V characteristics showed noticeable deterioration with over 8 hour radiations. Specifically, the saturation current of the control devices was ≈ 25 nA increasing to 1 μA and 10 μA for the 5.5-hour and 8.2-hour radiated samples, respectively. The turn-on voltage of the control devices (≈ 0.85 V) decreased with the irradiated sample (≈ 0.75 V for 5.5-hour and ≈ 0.5 V for 8.2-hour exposures), implying noticeable radiation damage occurred at the heterojunction. The higher values of the ideality factor for irradiated devices (n > 2.2) compared to that of the control devices (n ≈ 1.3) also support the deterioration of the p-n junction. We observed the notable decrease in shunt resistance (RSH) and the increase in series resistance (Rs) with the neutron dose. It is possible that Cu ions introduced during the CuCl2 treatment may migrate into CdTe grain boundaries (GBs). The presence of Cu ions at GBs can create additional leakage paths for photocarrier transport, deteriorating the overall PV performance. We estimated the radiation dose of CdTe in comparison to Si (conventional PV) using a UUTR model (e.g., MCNP6 2D UTR Reactor simulations). In this model, we simulated Si and CdTe at the center point of the triangular fuel lattice and used an “unperturbed flux” tally in the water. Our simulations yielded a dose rate of 6916 Gy/s of neutrons and 16 Gy/s of photons for CdTe, and 1 Gy/s of neutrons and 21 Gy/s of photons for Si (doses +/- <1%). The large dose rate of neutrons in CdTe is mainly attributed to the large thermal neutron absorption cross-section of 113Cd. Based on this estimation, we calculate that the exposure of our CdTe PVs is equivalent to several million years in LEO (Low-Earth Orbit), or about 10,000 years for Si in LEO. Currently, we are working on a low-dose neutron/photon radiation on CdTe PVs and their light I-Vs and microstructural characterizations to gain better understanding on the degradation of CdTe PVs.
Khanal, Megh N; Whiteside, Vincent R; Parashar, Mritunjaya; Merckx, Tamara; Sharma, Mohin; Kuang, Yinghuan; Aguirre, Aranzazu; Afshari, Hadi; Hamtaei, Sarallah; Aernouts, Tom; et al
(, Journal of Physics: Energy)
Irvine, John
(Ed.)
Abstract Here, the radiation hardness of metal halide perovskite solar cells exposed to space conditions versus the effects of environmental degradation are assessed. The relative response of the constituent layers of the architecture to radiation is analyzed, revealing a general resilience of the structure when assessed across varying proton energy levels and fluences. However, despite the tolerance of the structure to irradiation, sensitivity to environmental degradation is observed during the transit of the device between the radiation and characterization facilities. Experimental evidence suggests the NiOx/perovskite interface is particularly sensitive to the effects of humidity and/or temperature exposure, while the irradiation of the devices appears to induce thermally activated annealing: improving the solar cells upon radiation exposure.
Metal halide perovskite (MHP) solar cells are promising aerospace power sources given their potential as inexpensive, lightweight, and resilient solar electricity generators. Herein, the intrinsic radiation tolerance of unencapsulated methylammonium lead iodide/chloride (CH3NH3PbI3-xClx) films was isolated. Spatially resolved photoluminescence (PL) spectroscopy and confocal microscopy revealed the fundamental defect physics through optical changes as films were irradiated with 4.5 MeV neutrons and 20 keV protons at fluences between 5×1010 and 1×1016 p+/cm2. As proton radiation increased beyond 1×1013 p+/cm2, defects formed in the film, causing both a decrease in photoluminescence intensity and a 30% increase in surface darkening. All proton irradiated films additionally exhibited continuous increase of energy bandgaps and decreasing charge recombination lifetimes with increasing proton fluences. These optical changes in the absorber layer precede performance declines detectable in standard current-voltage measurements of complete solar cell devices and therefore have the potential of serving as early indicators of radiation tolerance.
Kirmani, Ahmad R., Durant, Brandon K., Grandidier, Jonathan, Haegel, Nancy M., Kelzenberg, Michael D., Lao, Yao M., McGehee, Michael D., McMillon-Brown, Lyndsey, Ostrowski, David P., Peshek, Timothy J., Rout, Bibhudutta, Sellers, Ian R., Steger, Mark, Walker, Don, Wilt, David M., VanSant, Kaitlyn T., and Luther, Joseph M. Countdown to perovskite space lunch: Guidelines to performing relevant radiation-hardness experiments. Retrieved from https://par.nsf.gov/biblio/10327489. Joule 6.5 Web. doi:https://doi.org/10.1016/j.joule.2022.03.004.
Kirmani, Ahmad R., Durant, Brandon K., Grandidier, Jonathan, Haegel, Nancy M., Kelzenberg, Michael D., Lao, Yao M., McGehee, Michael D., McMillon-Brown, Lyndsey, Ostrowski, David P., Peshek, Timothy J., Rout, Bibhudutta, Sellers, Ian R., Steger, Mark, Walker, Don, Wilt, David M., VanSant, Kaitlyn T., & Luther, Joseph M. Countdown to perovskite space lunch: Guidelines to performing relevant radiation-hardness experiments. Joule, 6 (5). Retrieved from https://par.nsf.gov/biblio/10327489. https://doi.org/https://doi.org/10.1016/j.joule.2022.03.004
Kirmani, Ahmad R., Durant, Brandon K., Grandidier, Jonathan, Haegel, Nancy M., Kelzenberg, Michael D., Lao, Yao M., McGehee, Michael D., McMillon-Brown, Lyndsey, Ostrowski, David P., Peshek, Timothy J., Rout, Bibhudutta, Sellers, Ian R., Steger, Mark, Walker, Don, Wilt, David M., VanSant, Kaitlyn T., and Luther, Joseph M.
"Countdown to perovskite space lunch: Guidelines to performing relevant radiation-hardness experiments". Joule 6 (5). Country unknown/Code not available. https://doi.org/https://doi.org/10.1016/j.joule.2022.03.004.https://par.nsf.gov/biblio/10327489.
@article{osti_10327489,
place = {Country unknown/Code not available},
title = {Countdown to perovskite space lunch: Guidelines to performing relevant radiation-hardness experiments},
url = {https://par.nsf.gov/biblio/10327489},
DOI = {https://doi.org/10.1016/j.joule.2022.03.004},
abstractNote = {Perovskite photovoltaics (PVs) are under intensive development for promise in terrestrial energy production. Soon, the community will find out how much of that promise may become reality. Perovskites also open new opportunities for lower cost space power. However, radiation tolerance of space environments requires appropriate analysis of relevant devices irradiated under representative radiation conditions. We present guidelines designed to rigorously test the radiation tolerance of perovskite PVs. We review radiation conditions in common orbits, calculate nonionizing and ionizing energy losses (NIEL and IEL) for perovskites, and prioritize proton radiation for effective nuclear interactions. Low-energy protons (0.05–0.15 MeV) create a representative uniform damage profile, whereas higher energy protons (commonly used in ground-based evaluation) require significantly higher fluence to accumulate the equivalent displacement damage dose due to lower scattering probability. Furthermore, high-energy protons may ‘‘heal’’ devices through increased electronic ionization. These procedural guidelines differ from those used to test conventional semiconductors.},
journal = {Joule},
volume = {6},
number = {5},
author = {Kirmani, Ahmad R. and Durant, Brandon K. and Grandidier, Jonathan and Haegel, Nancy M. and Kelzenberg, Michael D. and Lao, Yao M. and McGehee, Michael D. and McMillon-Brown, Lyndsey and Ostrowski, David P. and Peshek, Timothy J. and Rout, Bibhudutta and Sellers, Ian R. and Steger, Mark and Walker, Don and Wilt, David M. and VanSant, Kaitlyn T. and Luther, Joseph M.},
editor = {Earis, Philip}
}
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