Mixing Matters: Nanoscale Heterogeneity and Stability in Metal Halide Perovskite Solar Cells

Abstract

The structural stability of the metal halide perovskite (MHP) absorber material is crucial for the long-term solar cell stability in this thin-film photovoltaic technology. Here, we use mixed A-site FA 0.83 Cs 0.17 PbI 3 to demonstrate that nanoscale compositional heterogeneity can serve as initiation sites for more macroscale,

Initializing film homogeneity to retard phase segregation for stable perovskite solar cells

“…The initial increase of U index could be observed in some cases, in which a large number of small segregation domains were dissolved to form larger ones (supplementary materials). It reveals the determinant impact of the initial state on the segregation dynamics, which were in good agreement with the experimental data reported elsewhere ( 23 ).…”

“…Most studies of phase segregation of mixed perovskites focus on film aging to understand cation and anion migration, the formation and development of nanoscale clusters (14)(15)(16), thermodynamic driving forces (17,18), and their impacts on film properties and device performance (12,(19)(20)(21)(22)(23). Effective strategies such as relaxing residual strain and incorporating low-dimension perovskites can retard phase segregation by suppressing ion migration (5,24,25).…”

Ethylenediamine Addition Improves Performance and Suppresses Phase Instabilities in Mixed-Halide Perovskites

“…These data help explain the improved stability and device performance. The increased PLQE indicates a reduction in trap density in the EDA-1 films, facilitating larger quasi-Fermi-level splitting under illumination and therefore increased V OC , − and additionally, the improved homogeneity could help improve V OC of the EDA-1 films by reducing pinning to the low-bandgap regions of the film, which is a common problem in complex semiconductors. , Moreover, it has been shown recently that compositional inhomogeneity of the perovskite phase is the primary cause of phase instability in FA 1– x Cs 0.x Pb­(I 1– y Br y ) 3 perovskites. − Figure S10 shows the formation of “wrinkled” − films when using a higher precursor solution concentration (1.45 M). Even in this case, EDA-1 films show more homogeneous PL intensity and wavelength distributions compared to EDA-0.…”

Antimony-doped enhanced photoluminescence quantum yield in zero-dimensional lead-free metal halide Rb2CsBiCl6 crystals

“…Metal halides exhibit unprecedented structural flexibilities and tunable photophysical properties, making them excellent optoelectronic functional materials which are used in many fields, such as photovoltaic cells, 1 light-emitting diodes (LEDs), 2–4 X-ray scintillation, and nonlinear optical (NLO) fields. 5,6 In particular, lead-free metal halides as an emerging class of green materials have evoked more interest because the toxicity and instability of Pb-based perovskites have hindered their applications despite their excellent properties.…”