Tuning Molecular Interactions for Highly Reproducible and Efficient Formamidinium Perovskite Solar Cells via Adduct Approach

Abstract

The Lewis acid-base adduct approach has been widely used to form uniform perovskite films, which has provided a methodological base for the development of high-performance perovskite solar cells. However, its incompatibility with formamidinium (FA)-based perovskites has impeded further enhancement of photovoltaic performance and stability. Here, we report an efficient and reproducible method to fabricate highly uniform FAPbI films via the adduct approach. Replacement of the typical Lewis base dimethyl sulfoxide (DMSO) with N-methyl-2-pyrrolidone (NMP) enabled the formation of a stable intermediate adduct phase, which can be converted into a uniform and pinhole-free FAPbI film. Infrared and computational analyses revealed a stronger interaction between NMP with the FA cation than DMSO, which facilitates the formation of a stable FAI·PbI·NMP adduct. On the basis of the molecular interactions with different Lewis bases, we proposed criteria for selecting the Lewis bases. Owed to the high film quality, perovskite solar cells with the highest PCE over 20% (stabilized PCE of 19.34%) and average PCE of 18.83 ± 0.73% were demonstrated.

Efficient Passivation with Lead Pyridine‐2‐Carboxylic for High‐Performance and Stable Perovskite Solar Cells

“…Many volatile molecules have been introduced to retard the crystal growth and minimize the contents of GBs based on the Lewis acid-based theory, such as H 2 O, [27] dimethyl sulfoxide (DMSO), [12] N-methyl-2-pyrrolidone (NMP), [28] and pyridine. Many volatile molecules have been introduced to retard the crystal growth and minimize the contents of GBs based on the Lewis acid-based theory, such as H 2 O, [27] dimethyl sulfoxide (DMSO), [12] N-methyl-2-pyrrolidone (NMP), [28] and pyridine.…”

The Role of Diammonium Cation on the Structural and Optoelectronic Properties in 3D Cesium–Formamidinium Mixed‐Cation Perovskite Solar Cells

“…However, using diammonium cations with ammonium group at both sides to electrostatically connect the adjacent inorganic slabs in 3D perovskites have been rarely reported. To date, only the defect passivation effect as a result of the Lewis acid nature of ammonium cations has been reported . It is still not clear how the diammonium cations would affect the crystallization and therefore the optoelectronic properties of the perovskites which is, however, vital for the development of highly efficient and stable PSCs.…”

Dynamic Antisolvent Engineering for Spin Coating of 10 × 10 cm2 Perovskite Solar Module Approaching 18%

“…Herein, a simple dynamic antisolvent quenching (DAS) process is presented to understand large-area uniform perovskite films to obtain an efficient perovskite solar module. [17,18] However, this method requires the antisolvent, homogenously and quickly, to interact with the wet perovskite film to precipitate uniform solid perovskite films. A champion module device (10 Â 10 cm 2 ) with efficiency of 17.82% (another module with certified efficiency of 17.4%) is obtained using DAS process.…”

“…[7][8][9][10][11][12][13] To date, MA-based PSCM reported by Huang et al with an attractive PCE of 14.6% at an aperture area of 57.2 cm 2 has the largest area and the highest performance. [17,18] However, this method requires the antisolvent, homogenously and quickly, to interact with the wet perovskite film to precipitate uniform solid perovskite films. [14][15][16] For the more stable formamidine (FA)-based mixed-cation perovskite, there are few studies because when compared with MA-based perovskite, the control of nucleation and crystal growth is much more difficult in large-area FA-based perovskite films.…”