Isomeric multi-hydrogen-bonding enables blue perovskite LEDs

Despite huge progress accomplished in perovskite light-emitting diodes (PeLEDs), the electroluminescence performance of blue PeLEDs lags far behind, constraining the widespread application of PeLED technology for vibrant full-colour displays1,2,3,4,5. The wider bandgaps of blue emitters require higher working voltages of corresponding electroluminescent devices, intensifying the octahedral instability of perovskites with ionic nature6,7. Here we report efficient and stable PeLEDs with saturated blue emissions by constructing hydrogen-bonding networks formed within perovskite and at the interface using isomeric molecules. The O-benzylhydroxylamine hydrochloride (OBCl) between the hole transport layer and the emitter acts as hydrogen-bonding donor, binding to the perovskite inorganic framework, which enhances the perovskite structural stability and decreases the hole energy barrier due to the large dipole moment. The isomeric N-benzylhydroxylamine hydrochloride (NBCl) added into the perovskite provides acceptor and donor sites for forming hydrogen bonding with the OB+ and the perovskite. The isomeric molecular hydrogen bonding reinforces the preferential orientation of perovskite films induced by OB+ interfacial molecules, improving the carrier mobility and further enhancing material stability. We demonstrate, as a result, blue PeLEDs with external quantum efficiencies of 16.8% at 463 nm and 22.0% at 468 nm, as well as significantly improved device stability, representing state-of-the-art performance among pure- and deep-blue PeLEDs.