Enhancing efficiency and stability of perovskite solar cells through two-step deposition method with the addition of cesium halides to PbI2 precursor

Perovskite films with few defects play a key role in preparing high-performance perovskite solar cells (PSCs). Here, cesium halides, such as CsCl, CsBr, and CsI, were introduced as a modulator into 1st PbI2 precursor for manipulating the crystallization of perovskite films. By introducing CsI dense homogeneous perovskite films with high crystallinity, preferential orientation, and a pure black perovskite phase were prepared. In addition, the carrier lifetime of perovskite films was significantly increased because of the suppressed nonradiative recombination. Correspondingly, the power conversion efficiency (PCE) of small-area devices using CsI regulation was increased from 17.45 to 20.29%. Furthermore, the device showed excellent stability maintaining 75% of its initial PCE after 350 h of continuous irradiation. This study demonstrates that CsI-added is a reliable way to prepare PSCs for practical applications.

Automated summary

Cesium halides, such as CsCl, CsBr, and CsI, were introduced as a modulator in the precursor of perovskite films to manipulate their crystallization. The addition of CsI resulted in dense homogeneous perovskite films with high crystallinity, preferential orientation, and a pure black perovskite phase. The carrier lifetime of the perovskite films was significantly increased, leading to an improvement in the power conversion efficiency (PCE) of the small-area devices from 17.45% to 20.29%. The devices also exhibited excellent stability, maintaining 75% of the initial PCE after 350 hours of continuous irradiation. This study demonstrates the reliable application of CsI regulation for preparing high-performance perovskite solar cells.