A Novel Strategy for Scalable High‐Efficiency Planar Perovskite Solar Cells with New Precursors and Cation Displacement Approach

Abstract

Methylammonium iodide (MAI) and lead iodide (PbI ) have been extensively employed as precursors for solution-processed MAPbI perovskite solar cells (PSCs). However, the MAPbI perovskite films directly deposited from the precursor solutions, usually suffer from poor surface coverage due to uncontrolled nucleation and crystal growth of the perovskite during the film formation, resulting in low photovoltaic conversion efficiency and poor reproducibility. Herein, propylammonium iodide and PbI are employed as precursors for solution deposition of propylammonium lead iodide (PAPbI ) perovskite film. It is found that the precursors have good film formability, enabling the deposition of a large-area and homogeneous PAPbI perovskite film by a scalable dip-coating technique. The dip-coated PAPbI film is then subjected to an organic-cation displacement reaction, resulting in MAPbI film with high surface coverage and crystallinity. With the MAPbI film as the light absorber, planar PSCs are fabricated, and stabilized power conversion efficiencies of 19.27% and 15.68% can be achieved for the devices with active areas of 0.09 and 5.02 cm , respectively. The technology reported here provides a robust and efficient approach to fabricate large-area and high-efficiency perovskite cells for practical application.

A Cation‐Exchange Approach for the Fabrication of Efficient Methylammonium Tin Iodide Perovskite Solar Cells

“…Firstly, a hydrazinium tin iodide (N 2 H 5 SnI 3 , HASnI 3 ) layer was deposited by a simple solution technique. Then, the HASnI 3 film was transformed in situ into MASnI 3 in an methylamine (CH 3 NH 2 ; MA) atmosphere through an organic cation displacement approach . With this route, a smooth and dense MASnI 3 film formed with large micrometer‐sized grains and high crystallinity.…”

“…The conversion from HASnI 3 into MASnI 3 is rapid with the film color change from pale yellow to black upon exposing the film in the MA atmosphere. No liquid intermediate phase was observed during the conversion process, similar to those reported previously . The conversion was proceeded through an in situ organic cation exchange reaction [Eq.…”

From 1D to 3D: Fabrication of CH3NH3PbI3 Perovskite Solar Cell Thin Films from (Pyrrolidinium)PbI3 via Organic Cation Exchange Approach

“…However, the grain size in the film is usually about 100–200 nm due to rapid nucleation in the process . Previously, we reported high‐quality perovskite films fabricated from low‐dimensional perovskite films via the organic cation exchange approach under CH 3 NH 2 atmosphere at an elevated temperature . In this work, a new crystal form of 1D (pyrrolidinium)PbI 3 ( 1 , orthorhombic phase) was synthesized and characterized.…”

A Cation‐Exchange Approach for the Fabrication of Efficient Methylammonium Tin Iodide Perovskite Solar Cells

“…Then, the HASnI 3 film was transformed in situ into MASnI 3 in an methylamine (CH 3 NH 2 ;M A) atmosphere through an organic cation displacement approach. [29,30] With this route, as mooth and dense MASnI 3 film formed with large micro-meter-sized grains and high crystallinity.M oreover,t he undesirable oxidation of Sn 2+ to Sn 4+ could be effectively suppressed by the reducing agent hydrazine generated inside the film during the cation displacement reaction. With the film as alight absorber,mesoporous heterojunction solar cells were fabricated with amaximum power conversion efficiency of 7.13 %.…”

“…Thec onversion from HASnI 3 into MASnI 3 is rapid with the film color change from pale yellow to black upon exposing the film in the MA atmosphere.N ol iquid intermediate phase was observed during the conversion process,s imilar to those reported previously. [29,30] Thec onversion was proceeded through an in situ organic cation exchange reaction [Eq. (1)].…”