Performance improvement of blue quantum dot light-emitting diodes by facilitating electron transportation and suppressing electroplex emission

Defect passivation and electron band energy regulation of a ZnO electron transport layer through synergetic bifunctional surface engineering for efficient quantum dot light-emitting diodes

“…For the state-of-the-art QLED device, ZnO NPs are the most commonly employed as the electron transport layer (ETL) because of their high electron mobility and optimal energy band alignment. 9–11 However, QLEDs with the ZnO ETL generally lead to charge imbalance in the QDs due to a non-negligible energetic barrier for hole injection. Consequently, the over-accumulation of electrons at the hole transport layer (HTL) and QD interface leads to increasing non-radiative Auger recombination.…”

Optimizing Device Efficiency and Lifetime through Positive Ageing in Quantum Dot Light-Emitting Diodes

“…Most previous ageing studies were related to the device’s electrical properties, while rarely focusing on the transform of the light-emitting region and possible heterojunction change. − In addition to the commonly used current–brightness–voltage characterization method, we evaluate the luminescence uniformity at different ageing times using an imaging luminance meter. More importantly, an in-depth investigation of the Kelvin probe and surface photovoltage technique has been used to analyze the changes of the heterojunction in the QLEDs during ageing, thereby establishing the relationship between the built-in electric field and the improvement of device efficiency.…”

Long-term spontaneous negative aging behavior of encapsulated blue quantum dot light emitting devices: the influence of the hole transport material

“…In the case of blue QLEDs in particular, such encapsulation is also essential for obtaining high efficiency. 13,16 Surprisingly, a so-called positive aging behavior, i.e. , a spontaneous gradual improvement in device performance including its efficiency, is often observed in encapsulated QLEDs in the short term ( i.e.…”

“…during the first 10's hours after encapsulation). 13,16–20 In the long term, however, the trend reverses and the devices exhibit a spontaneous gradual deterioration in efficiency that occurs even without any electric bias, often referred to as spontaneous negative aging. 16,17,19,21 The underlying mechanism for this spontaneous negative aging behavior in encapsulated QLEDs remains unclear.…”