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J Phys Chem Lett ; 11(14): 5563-5568, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32564599


Recent studies have shown that charge transport interlayers with low gas permeability can increase the operational lifetime of perovskite solar cells serving as a barrier for migration of volatile decomposition products from the photoactive layer. Herein we present a hybrid hole transport layer (HTL) comprised of p-type polytriarylamine (PTAA) polymer and vanadium(V) oxide (VOx). Devices with PTAA/VOx top HTL reach up to 20% efficiency and demonstrate negligible degradation after 4500 h of light soaking, whereas reference cells using PTAA/MoOx as HTL lose ∼50% of their initial efficiency under the same aging conditions. It was shown that the main origin of the enhanced device stability lies in the higher tolerance of VOx toward MAPbI3 compared to the MoOx interlayer, which tends to facilitate perovskite decomposition. Our results demonstrate that the application of PTAA/VOx hybrid HTL enables long-term operational stability of perovskite solar cells, thus bringing them closer to commercial applications.

J Phys Chem Lett ; 11(1): 333-339, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31838849


We report the first systematic assessment of intrinsic photothermal stability of a large panel of complex lead halides APbX3 incorporating different univalent cations (A = CH3NH3+, [NH2CHNH2]+, Cs+) and halogen anions (X = Br, I) using a series of analytical techniques such as UV-vis and X-ray photoelectron spectroscopy, X-ray diffraction, EDX analysis, atomic force and scanning electron microscopy, ESR spectroscopy, and mass spectrometry. We show that heat stress and light soaking induce a severe degradation of perovskite films even in the absence of oxygen and moisture. The stability of complex lead halides increases in the order MAPbBr3 < MAPbI3 < FAPbI3 < FAPbBr3 < CsPbI3 < CsPbBr3, thus featuring all-inorganic perovskites as the most promising absorbers for stable perovskite solar cells. An important correlation was found between the stability of the complex lead halides and the volatility of univalent cation halides incorporated in their structure. The established relationship provides useful guidelines for designing new complex metal halides with immensely improved stability.

ACS Appl Mater Interfaces ; 11(24): 21741-21748, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31091872


We explored the radiation stability of carbazole-based electron-donor conjugated polymers, acceptor fullerene derivative [60]PCBM, and their blends as active layer components of organic solar cells. An exposure to Î³ rays induced evident degradation effects in bulk samples of the pristine fullerene acceptor ([60]PCBM) and two investigated electron-donor conjugated polymers: PCDTBT and PCDTTBTBTT. The most severe radiation damage occurred in [60]PCBM as can be concluded from the significant losses in open circuit voltage, fill factor, and efficiency of photovoltaic (PV) devices comprising the exposed fullerene acceptor. Conjugated polymers PCDTBT and PCDTTBTBTT showed substantially different radiation stabilities: the samples of PCDTTBTBTT exposed to 200 Gy lost ∼25% of their nominal photovoltaic efficiency due to a substantial decay of all device parameters, while PCDTBT alone showed just a minor aging under the same conditions. The fullerene-polymer composites were much more resistant with respect to the radiation damage than the bulk samples of pristine materials. In particular, the PCDTBT/[60]PCBM composite films demonstrated an outstanding radiation stability while maintaining more than 80% of the initial photovoltaic efficiency after exposure to γ rays with a maximum absorbed dose of 6500 Gy. Considering an average annual radiation dose of 160 Gy according to the NASA estimations for satellites at geocentric Earth orbits, organic solar cells based on PCDTBT/[60]PCBM blends hold a promise to deliver lifetimes well above 10 years. The revealed impressive radiation stability of PCDTBT/[60]PCBM blends in combination with other advantages of organic solar cells, for example, their mechanical flexibility and lightweight, points to a bright future of this PV technology in space industry applications.

J Phys Chem Lett ; 10(4): 813-818, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30621392


We report on the impact of γ radiation (0-500 Gy) on triple-cation Cs0.15MA0.10FA0.75Pb(Br0.17I0.83)3 perovskite solar cells. A set of experiments was designed to reveal the individual contributions of the hole-collecting bottom electrode, perovskite absorber, and electron transport layer (ETL) to the overall solar cell degradation under radiation exposure. We show that the glass/ITO/PEDOT:PSS hole-collecting electrode withstands a 500 Gy dose without any losses in the solar cell performance. In contrast, the perovskite absorber films and PC61BM ETL are very sensitive to γ rays, as can be concluded from the radiation-induced decay of the solar cell efficiency by ∼32-41%. Red shift of the perovskite emission bands and strong enhancement of the photoluminescence suggest that γ rays induce phase segregation of iodine-rich and bromine-rich domains, which represents the first reported example of the radiation-induced halide phase separation in perovskite films. The degradation pathway revealed here emphasizes the need for developing a new generation of metal halide absorbers and ETL materials with improved radiation stability to enable potential space applications of perovskite photovoltaics.