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Perovskite solar cells have attracted a great deal of attention thanks to their high efficiency, ease of manufacturing, and potential low cost. However, the stability of these devices is considered their main drawback and needs to be addressed. Mesoporous carbon perovskite solar cells (m‐CPSC), consisting of three mesoporous layers (TiO2/ZrO2/C) infiltrated with CH3NH3PbI3 (MAPI) perovskite, have presented excellent lifetimes of more than 10 000 h when the additive NH2(CH2)4CO2HI (5‐ aminovaleric acid iodide; 5‐AVAI) is used to modify the perovskite structure. Yet, the role of 5‐AVAI in enhancing the stability has yet to be determined. Here, superoxide‐mediated degradation of MAPI m‐CPSC with and without the 5‐AVAI additive is studied using the fluorescence probe dihydroethidium for superoxide detection. In situ X‐ray diffractometry shows that aminovaleric acid methylammonium lead iodide (AVA‐MAPI) perovskite infiltrated in mesoporous layers presents higher stability in an ambient environment under illumination, evidenced by a slower decrease of the MAPI/PbI2 peak ratio. Superoxide yield measurements demonstrate that AVA‐MAPI generates more superoxide than regular MAPI when deposited on glass but generates significantly less when infiltrated in mesoporous layers. It is believed that superoxide formation in m‐CPSC is dependent on a combination of competitive factors including oxygen diffusion, sample morphology, grain size, and defect concentration. [ABSTRACT FROM AUTHOR]

Co-sensitisation of methylammonium lead tri-bromide perovskite solar cells with red (D205) and blue (SQ2) organic dyes improves device efficiencies and allows device colour tuning. Sensitising the film after perovskite crystallisation produces higher device efficiencies (2.6% SQ2, 3.1% D205) than perovskite-only devices (2%) and devices sensitised before the perovskite layer deposition (1.5% SQ2, 2.0% D205). [ABSTRACT FROM AUTHOR]

We report a solvent-free approach to synthesizing organolead perovskites by using solid state reactions to coat perovskite crystals onto Al2O3 or TiO2 nanoparticles followed by addition of terpineol affording perovskite inks. We have bar cast these inks to produce photoactive perovskite thin films which are significantly more stable to humidity than solution-processed films. This new method also avoids the use of toxic DMF solvent. [ABSTRACT FROM AUTHOR]

Organolead trihalide perovskite solar cells based upon the co-deposition of a combined Al2O3–perovskite layer at T ＜ 110 °C are presented. We report an average PCE = 7.2% on a non-sintered Al2O3 scaffold in devices that have been manufactured from a perovskite precursor containing 5 wt% Al2O3 nanoparticles. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Study of the fluorescence properties of MAPI perovskite in air and nitrogen. • Changes in fluorescence are correlated with morphology changes through XRD. • Evidence that degradation occurs at the same time as photobrightening. • Highlights the complex nature of fluorescence behaviour of perovskite thin-films. Abstract Organic-inorganic perovskite materials, such as methylammonium lead iodide, are good candidates for the next generation of solar cells with an impressive certified 23.7% power conversion efficiency. However, their development is impeded by their poor stability to oxygen, moisture, light and combinations of these. The bulk photoluminescence of perovskite films is extremely sensitive to the environment (humidity, light intensity, temperature, atmosphere) and has been shown to undergo rapid photobrightening and photodarkening. Here, we study the changes in photoluminescence behaviour (intensity, wavelength and full-width-at-half-maximum) in both air and nitrogen and correlate this with changes in the crystal structure of the films under illumination. We show that photodarkening is caused by degradation of the perovskite and that both brightening and some degree of darkening are competitive processes occurring simultaneously. During photobrightening the fluorescence emission spectrum red-shifts which can be explained by the halide redistribution and passivation of trap states in the perovskite. We conclude that care is required when measuring fluorescence of perovskite due to the important variations in intensity, emission wavelength and full-width-at-half-maximum. [ABSTRACT FROM AUTHOR]