Over 8% efficient CsSnI₃-based mesoporous perovskite solar cells enabled by two-step thermal annealing and surface cationic coordination dual treatment

Abstract

All inorganic tin halide perovskite compounds, such as CsSnI3, have attracted attention in the field of solar cells due to their eco-friend property. It is quite a challenge to fabricate...

Efficient and Stable Mesoporous CsSnI3 Perovskite Solar Cells via Imidazolium‐Based Ionic Liquid Additive

“…Stage (2) due to a strong coordination ability of EMIM + and Ac − ions, part of SnI 2 lattice units preferentially coordinate with EMIM + and Ac − . During the thermal annealing process of two‐step annealing procedure at 40 and 70 °C, respectively, [ 28 ] the perovskite crystallization would like to occur between CsI and SnI 2 by overcoming the reaction activation energy barrier for crystal formation. Meanwhile, the surplus EMIM + and Ac − ions could be linked to the surface undercoordinated Sn 2+ of as‐formed CsSnI 3 perovskite crystals.…”

“…Figure S3a-d, Supporting Information, presents the XPS Sn 3d bands spectra of CsSnI 3 films added with different concentrations of EMIMAc, where the deconvolution of six peaks at 486.7 and 495.2 eV, 486.9 and 495.4 eV, and 487.5 and 496.0 eV are related to Sn 2þ , undercoordinated Sn 2þ , and Sn 4þ , respectively. [28] The calculated content of surface undercoordinated Sn 2þ and Sn 2þ is shown in Figure 2a. We can clearly find that the addition of EMIMAc can not only effectively reduce the content of undercoordinated Sn 2þ on the surface, but also decrease the proportion of surface Sn 2þ oxidized.…”

“…[27] Most widely used materials for surface passivation approach in perovskite films include Lewis bases/acids, organic halide salts, and polymers. [26][27][28] Among them, most additives are insulators, which may hinder the effective carrier extraction at the interface between different active layers due to their poor conductivity. This also could cause many other unfavorable effects such as the weak reproducibility of PSCs due to an uneven molecular weight distribution.…”

Full Life-Cycle Lead Management and Recycling Transparent Conductors for Low-Cost Perovskite Solar Cell

“…Despite their promise, there still exist the toxicity issues associated with the Pb content of high-performing PSCs during a photovoltaic device’s lifetime . A direct strategy to avoid a potential threat to the environment is to completely replace the Pb counterpart in the perovskite crystal structure, but all currently used lead-free perovskites like tin-containing perovskite are facing intractable problems such as poor stability and low PCE. − Apart from the replacement of lead, in recent years, some explorations to immobilize Pb and prevent them escaping from perovskite into the environment have been performed, through either polymer protection network building, metal-framework capture, or ion migration inhibition. − Particularly, inhibiting Pb ion migration by one-step introduction of an additive into a precursor to form a robust perovskite is a relatively facile and green method, compared to the in situ polymerization process of a gradient-annealing-dependent polymer network and multistep synthesis process of a heavy-metal-containing metal framework. , Various additives have been explored to inhibit Pb ion migration in perovskite . Of these, green pseudo halide (pseudo-X) ions with a cheap market price (e.g., HCOO – and Ac – ) as additives have been demonstrated to be effective in inhibiting Pb ion migration via the strong interaction with undercoordinated Pb in perovskite, in keeping with a high PCE. − …”

Continuous Modification of Perovskite Film by a Eu Complex to Fabricate the Thermal and UV-Light-Stable Solar Cells

“…The excellent performance is impressive in thin-film devices obtained by low-temperature solution processing . However, it is worth noting that this method inevitably produces several defects on the bulk and surfaces of the film. − The defects at the surface and grain boundaries of perovskite films contribute to PSCs’ performance deterioration, and they are also some of the main reasons for their poor stability. , Moreover, the inherent “soft” crystal lattice of perovskite materials makes the PSCs vulnerable to aging stresses, such as UV light, moisture, oxygen, electric field, and thermal annealing. − Currently, various strategies have been applied to enhance the resistance of PSCs to the operational environment, − which has increased the survival of PSCs from a few minutes at first to several years currently. − Many efforts have been achieved in the high-performance research of PSCs, − but their life span is still a huge barrier when translating PSCs from laboratory to commercial products …”