Synthesis of stable iodoplumbate and perovskite for efficient annealing-free device and long-term storage

As a next-generation photovoltaic device,perovskite solar cells are rapidly emerging.Nevertheless,both solution and device stability pose challenges for commercialization due to chemical degradation caused by internal and external factors.Especially,the decomposition of iodoplumbate in a perovskite solution hinders the long-term use of perovskite solutions.Moreover,the synthesis of stable perovskites at low temperature is important for stable devices and wide applications(flexible devices and high reproducibility).Herein,the critical composition of perovskite is found to obtain high stabilities of both iodoplumbate and perovskite crystals by utilizing CsPbBr_(3) and FAPbI_(3),exhibiting high device performance and long-term solution storage.The novel composition of CsPbBr_(3)-alloyed FAPbI_(3) not only crystallizes under annealing-free conditions but also demonstrates excellent iodoplumbate stability for 100 days(∼3000 h)without any degradation.Furthermore,high device stabilities are achieved over 2000 and 3000 h under extreme conditions of A.M.1.5 and 85℃/85%relative humidity,respectively.Overall,the device exhibited a high power conversion efficiency of 23.4%,and furthermore,CsPbBr_(3)-alloyed FAPbI_(3) was devoted to widen the applications in both flexible and carbon-electrode devices,thereby addressing both scientific depths and potential commercial materials.

Is p-Type Doping in TeO_(2)Feasible?

Wide-bandgap two-dimensional (2D) β-TeO_(2) has been reported as a high-mobility p-type transparent semiconductor [Nat. Electron. 4 277 (2021)], attracting significant attention. This "breakthrough" not only challenges the conventional characterization of TeO_(2) as an insulator but also conflicts with the anticipated difficulty in hole doping of TeO_(2) by established chemical trends. Notably, the reported Fermi level of 0.9 eV above the valence band maximum actually suggests that the material is an insulator, contradicting the high hole density obtained by Hall effect measurement. Furthermore, the detected residual Se and the possible reduced elemental Te in the 2D β-TeO_(2) samples introduces complexity, considering that elemental Se, Te, and Te_(1−x)Se_(x) themselves are high-mobility p-type semiconductors. Therefore, doubts regarding the true cause of the p-type conductivity observed in the 2D β-TeO_(2) samples arise. In this Letter, we employ density functional theory calculations to illustrate that TeO_(2), whether in its bulk forms of α-, β-, or γ-TeO_(2), or in the 2D β-TeO_(2) nanosheets, inherently exhibits insulating properties and poses challenges in carrier doping due to its shallow conduction band minimum and deep valence band maximum. Our findings shed light on the insulating properties and doping difficulty of TeO_(2), contrasting with the claimed p-type conductivity in the 2D β-TeO_(2) samples, prompting inquiries into the true origin of the p-type conductivity.