Lead acetate precursors for preparing CsPbI3 light harvester layers of inorganic perovskite solar cells.

• a-CsPbI 3 light harvester layers are prepared at low temperature without hydrogen iodide additive. • Lead acetate is used as the lead source of precursor solutions. • Ethylenediaminium iodide can cooperates with the lead acetate precursor. • The grain size of CsPbI 3 layers is increased and their trap density is reduced. • The power conversion efficiency and photo-stability of devices are improved. CsPbI 3 triggers strong interest in the photovoltaic community for their promising photoelectric property and nonvolatility. However, CsPbI 3 layers with a-phase crystal structure are difficult for preparation, and these layers easily degrade to non-photoactive δ-phase at room temperature. Tuning the composition of precursor solutions is an important method for improving the properties of CsPbI 3 layers. Herein, we prepare inorganic a-CsPbI 3 perovskite solar cells using lead acetate as the lead source, which is different from conventional precursors with lead iodide as the lead source. The lead acetate precursor needs neither incorporating hydrogen iodide nor preparing PbI 2 complex, and it is shown to enlarge the grain size, improve the crystallinity and reduce the trap density of CsPbI 3 layers. By cooperating the lead acetate precursor with EDAI 2 additive, the power conversion efficiency (PCE) of devices increases from 9.2% to 12.9% and the photo-stability of these devices is improved simultaneously. [ABSTRACT FROM AUTHOR]