Stable High-Efficiency Two-Dimensional Perovskite Solar Cells Via Bromine Incorporation

Abstract

Two-dimensional (2D) organic-inorganic perovskites as one of the most important photovoltaic material used in solar cells have attracted remarkable attention. These 2D perovskites exhibit superior environmental stability and wide tunability of their optoelectronic properties. However, their photovoltaic performance is far behind those of traditional three-dimensional (3D) perovskites. In this work, we demonstrate the power conversion efficiency (PCE) of 2D perovskite solar cells (PVSCs) is greatly improved from 3.01% for initial to 12.19% by the incorporation of PbBr2. The enhanced efficiency is attributed to superior surface quality, enhanced crystallinity, and the resulting reduced trap-state density. Furthermore, PbBr2 incorporated devices without encapsulation show excellent humidity stability, illumination stability, and thermal stability. This work provides a universal and viable avenue toward efficient and stable 2D PVSCs.

A Thienothiophene‐Based Cation Treatment Allows Semitransparent Perovskite Solar Cells with Improved Efficiency and Stability

“…The grazing incidence X-ray diffraction (GIXRD) showed a peak below 10°, which is commonly attributed to the formation of a 2D perovskite layer. [51][52][53] The observed peak at 5.10° for TTMAI-treated 3D perovskite (Figure 1d) was initially assigned to TTMA 2 PbI 4 2D perovskite (n = 1). To support our claim, 2D perovskite (n = 1) was formed by coating TTMAI and PbI 2 (2:1) on SnO 2 , and GIXRD analysis was performed, which revealed a peak at 5.60° (Figure 1d).…”

Impact of Humidity and Temperature on the Stability of the Optical Properties and Structure of MAPbI3, MA0.7FA0.3PbI3 and (FAPbI3)0.95(MAPbBr3)0.05 Perovskite Thin Films

“…Minimal variation of effective thickness with time for MA 0.7 FA 0.3 PbI 3 deposited on glass is observed compared to that observed for MAPbI 3 on glass ( Table 1 ) within a similar time interval. The improved stability of mixed MA + FA perovskite can be attributed to the larger size of the FA cation compared to MA leading to a more favorable tolerance factor [ 14 , 53 ]. The ionic radii of MA and FA are 2.16 and 2.53 Å [ 54 ], respectively, and a larger FA cation fraction in the perovskite results in a more ideal Goldschmidt tolerance factor closer to 1 [ 14 , 54 ].…”

“…The improved stability for (FAPbI 3 ) 0.95 (MAPbBr 3 ) 0.05 over MAPbI 3 and MA 0.7 FA 0.3 PbI 3 with temperature variations and humidity exposure is attributed to the incorporation of Br into the mixed MA + FA film. Previous research has shown that including a small amount of Br enhances the stability, suppresses ion migration, and reduces trap-state density [ 53 ]. According to Noh et al, upon incorporation of Br into MAPbI 3 for solar cell absorbers, there is an improvement in open circuit voltage (V OC ) from 0.87 to 1.13 V and an increase in fill factor (FF) from 0.66 to 0.74 [ 58 ].…”

“…Increases in these parameters is an indicator of good electronic film quality [ 36 ]. It has also been reported that replacing larger I ions with smaller Br ions results in a greater resistance to high humidity at room temperature [ 53 ]. Furthermore, perovskite films with mixed cations and mixed anions crystallize at much higher temperatures and exhibit greater degrees of crystalline order.…”

Two-Dimensional Hybrid Halide Perovskites: Principles and Promises

“…In order to bypass this obstacle, several researchers have turned to the familiar remedy employed in 3D perovskites: 226 the mixing of cations in the A-site in order to tune the tolerance factor. 227 Although this approach paid some dividends in terms of improved devices when the mixed compositions were employed to cast thin films, 107,128,228 the complete lack of structural characterization leaves the exact composition of the films in question. Nevertheless, in a few cases structural characterization has been achieved, showing that incorporation of FA is possible, as in the n = 4 DJ perovskite (3AMP)-(MA) 2.25 (FA) 0.75 Pb 4 I 13 (unpublished results in our laboratory).…”