image: The type II organic-inorganic intramolecular heterojunction can effectively boost the carrier spatial separation. Furthermore, the strong intermolecular interaction between the large π-conjugated cation and Pb–X inorganic counterpart is beneficial to preventing inorganic counterpart from being attacked by organic solvents and even water for a long term.
Credit: ©Science China Press
This study is led by associate professor Xu-Dong Wang, associate professor Long Jiang and professor Dai-Bin Kuang (Sun Yat-Sen University, China). They report a class of 1D perovskitoids (TzBIPY)Pb2X6 (X = Cl, Br, I) featuring a π-conjugated diamine cation (TzBIPY = 2.5-di(pyridin-4-yl)thiazolo[5.4-d]thiazole). The TzBIPY2+ cation with delocalized electrons directly contributes to the electronic structure and hence reduces the band gap. Notably, the Br-based material exhibits more efficient carrier separation and transport capacity due to the enhanced electronic conjugation along with a type II intramolecular heterojunction between conjugated organic cations and Pb–X octahedra. These characteristics enable (TzBIPY)Pb2Br6 to function as a high-performance photodetector with an exceptional photocurrent on/off ratio of 8.1 × 105 which surpasses that of previous three-dimensional perovskite benchmarks. Additionally, the π-conjugated cations act as dense protective shields for vulnerable Pb-X inorganic lattice against water attack resulting in impressive stability even after immersion in water for over 3000 h.
Journal
Science Bulletin