Efficient and Stable FASnI₃ Perovskite Solar Cells with Effective Interface Modulation by Low‐Dimensional Perovskite Layer

Abstract

The promising tin perovskite solar cells (PSCs) suffer from the oxidation of Sn2+ to Sn4+, leading to a disappointing conversion efficiency along with poor stability. In this work, phenylethylammonium bromide (PEABr) was employed to form an ultrathin, low‐dimensional perovskite layer on the surface of the FASnI3 (FA=formamidinium) absorber film to improve the interface of perovskite/PCBM ([6,6]‐phenyl‐C61‐butyricacid methyl) in the inverted planar device structure of the ITO (indium‐doped tin oxide)/PEDOT:PSS [poly(3,4‐ethylenedioxythiophene)/polystyrene sulfonate]/perovskite/[6,6]‐phenyl‐C61‐butyricacid methyl (PCBM)/BCP (2,9‐dimethyl‐4,7‐diphenyl‐1,10‐phenanthroline) electrode. The device efficiency was enhanced from 4.77 to 7.86 % by this PEABr treatment. A series of characterizations proved that this modification could improve the crystallinity of the FASnI3 perovskite by incorporating Br and forming an ultrathin, low‐dimensional perovskite layer at the interface, which led to the effective suppression of Sn2+ oxidation, improved band level alignment, and decreased defect density. These effects contributed to the clear enhancement of conversion efficiency. Moreover, this treatment also led to remarkably enhanced device stability, with approximately 80 % of the initial efficiency retained after 350 h light soaking, whereas the control device failed within 140 h. This work deepens our understanding of the suppression effect of PEABr on the oxidation of Sn2+ and paves a new way to fabricate promising tin halide PSCs by facile interface engineering.

Oriented Crystallization of Mixed‐Cation Tin Halides for Highly Efficient and Stable Lead‐Free Perovskite Solar Cells

“…[ 25 ] In addition, the PL peak intensity of the MA 0.25 FA 0.75 SnI 2.75 Br 0.25 perovskite film is apparently increased after MABr incorporation, indicating the suppressed non‐radiative trap‐assisted recombination (Figure 4d). [ 52–54 ] Furthermore, the time‐resolved PL spectra were measured and shown in Figure S7, Supporting Information, with the humidity of about 50% at ≈25 °C. The mixed MA 0.25 FA 0.75 SnI 2.75 Br 0.25 film displayed beyond 2‐fold longer time (3.52 ns) than that of the pristine FASnI 3 film (1.65 ns), further confirming the decreased trap state density after MABr incorporation.…”

Sensing the polar molecules MH3 (M = N, P, or As) with a Janus NbTeSe monolayer

“…TMDs have been demonstrated to be the most attractive materials since their transport characteristics can be modulated to enhance the sensitivity towards different gases due to the available electron in the d orbital of the transition metal as well as hybridization between transition metal and chalcogen elements. [11][12][13][14][15] Besides, the type (direct/indirect) and value of bandgap for TMDs can be tailored by stacking layers, strains or doping with foreign elements, which are highly appealing for nanoelectronics, electronic gas sensors and optoelectronic devices. For instance, previous studies reported that single and multi-layer MoS 2 and WS 2 field-effect transistor (FET) devices exhibit excellent sensitivity to a number of gas molecules, such as CO, CO 2 , NH 3 (5-50 ppm), NO and NO 2 (20 ppm) via changes in their resistivity induced by differences in their tendency to donate or accept charge from the substrates.…”

ASnX3—Better than Pb‐based Perovskite

“…deployed phenylethylammonium bromide (PEABr) onto the FASnI 3 surface to modify and improve its properties. [ 133 ] The crystallinity of the FASnI 3 was improved by incorporating Br and the formation of an ultrathin, low‐dimensional perovskite layer at the interface, which led to the effective suppression of Sn 2+ oxidation. Furthermore, the band alignment was improved and the defect density was decreased.…”