Functional Ionic Liquid Polymer Stabilizer for High-Performance Perovskite Photovoltaics.

The stability-related issues arising from the perovskite precursor inks, films, device structures and interdependence remain severely under-explored to date. Herein, we designed an ionic-liquid polymer (poly[Se-MI][BF 4 ]), containing functional moieties like carbonyl (C=O), selenium (Se + ), and tetrafluoroborate (BF 4 - ) ions, to stabilize the whole device fabrication process. The C=O and Se + can coordinate with lead and iodine (I - ) ions to stabilize lead polyhalide colloids and the compositions of the perovskite precursor inks for over two months. The Se + anchored on grain boundaries and the defects passivated by BF 4 - efficiently suppress the dissociation and migration of I - in perovskite films. Benefiting from the synergistic effects of poly[Se-MI][BF 4 ], high efficiencies of 25.10 % and 20.85 % were exhibited by a 0.062-cm 2 device and 15.39-cm 2 module, respectively. The devices retained over 90 % of their initial efficiency under operation for 2200 h.