Carrier balance and ion diffusive inhibition are crucial to the external quantum efficiency (EQE) and stability of perovskite quantum dot light-emitting diodes (PQLEDs). Herein, an inorganic ZnBr2 ligand is used to passivate the Br vacancy on the surface of the perovskite quantum dots and, thus, near-unity photoluminescence quantum yield is achieved. With respect to energy alignment and carrier balance, poly[bis(4-phenyl) (4-butylphenyl) amine] (poly-TPD) is chosen to match with 1,3,5-tris (1-phenyl-1H-benzimidazol-2-yl) benzene (TPBi), and the fabricated PQLEDs exhibit the maximum luminance as high as 92,279 cd m–2. In addition, an ultrathin Al2O3 layer is introduced between indium tin oxide (ITO) and poly(ethylene dioxythiophene):polystyrene sulfonate (PEDOT:PSS) via atomic layer deposition (ALD). The Al2O3 buffer layer can precisely control the hole transmission rate, balance the carrier injection, and realize the improvement of EQE from 2.86 to 4.81%. The T50 lifetime of the device is extended by about 30 times due to suppression of metal ion diffusion from ITO to the emission layer. Our work demonstrates the promising fabrication of highly efficient and stable PQLEDs via ALD interface engineering.
Operational stability remains the foremost concern delaying the commercialization of perovskite solar cells (PSCs). Ions diffusion from iodine-rich perovskite layer to metal electrode is one main reason for the irreversible devices degradation. Here we introduce chemically crosslinked TMTA (trimethylolpropane triacrylate) at both bulk perovskite layer and perovskite/PCBM interface to suppress the ions diffusion toward electrode. The TMTA in perovskite layer suppresses ions migration along grain boundaries and TMTA at perovskite/PCBM interface blocks ions diffusion toward electrode, owing to its continuous network structure and chemically inert nature. Diffusion experiment, permeation experiment and resistive random-access memory (RRAM) investigation confirm the effectively blocked ions diffusion in PSCs with TMTA whether under heat, light or electric field conditions. The resulting PSCs exhibit 7-fold improvement in operational stability at elevated temperature of 60 °C, retaining ~80% of initial efficiency after maximum power point tracking for 1000 h under continuous illumination. The PSCs with TMTA also exhibit good thermal stability and retain over 90% of the initial efficiency after aging at 60 °C for 1000 h.
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