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][BF4]), containing functional moieties like carbonyl (C=O), selenium (Se+), and tetrafluoroborate (BF4-) 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 BF4- efficiently suppress the dissociation and migration of I- in perovskite films. Benefiting from the synergistic effects of poly[Se-MI][BF4], 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.

Automated summary

The stability-related issues of perovskite precursor inks, films, device structures, and interdependence have not been explored sufficiently. In this study, a ionic-liquid polymer (poly[Se-MI][BF4]) was designed to stabilize the entire device fabrication process. The functional moieties of carbonyl (C=O), selenium (Se+), and tetrafluoroborate (BF4-) ions in the polymer effectively stabilized the lead polyhalide colloids and perovskite precursor inks. The poly[Se-MI][BF4] also suppressed the dissociation and migration of iodine (I-) in perovskite films with the help of anchored selenium ions and passivated defects by BF4-. High efficiencies of 25.10% and 20.85% were achieved by a 0.062-cm(2) device and 15.39-cm(2) module, respectively, with over 90% retention of initial efficiency after 2200 hours of operation.