Two-dimensional quantum dots have received a lot of attention in recent years due to their fascinating properties and widespread applications in sensors, batteries, white light-emitting diodes, photodetectors, phototransistors, etc. Atomically thin two-dimensional quantum dots derived from graphene, layered transition metal dichalcogenide, and phosphorene have sparked researchers’ interest with their unique optical and electronic properties, such as a tunable energy bandgap, efficient electronic transport, and semiconducting characteristics. In this review, we provide in-depth analysis of the characteristics of two-dimensional quantum dots materials, their synthesis methods, and opportunities and challenges for novel device applications. This analysis will serve as a tipping point for learning about the recent breakthroughs in two-dimensional quantum dots and motivate more scientists and engineers to grasp two-dimensional quantum dots materials by incorporating them into a variety of electrical and optical fields.

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Organic light-emitting diodes (OLEDs) have played a vital role in showing tremendous technological advancements for a better lifestyle, due to their display and lighting technologies in smartphones, tablets, television, and automotive industries. Undoubtedly, OLED is a mainstream technology and, inspired by its advancements, we have designed and synthesized the bicarbazole-benzophenone-based twisted donor–acceptor–donor (D-A-D) derivatives, namely DB13, DB24, DB34, and DB43, as bi-functional materials. These materials possess high decomposition temperatures (>360 °C) and glass transition temperatures (~125 °C), a high photoluminescence quantum yield (>60%), wide bandgap (>3.2 eV), and short decay time. Owing to their properties, the materials were utilized as blue emitters as well as host materials for deep-blue and green OLEDs, respectively. In terms of the blue OLEDs, the emitter DB13-based device outperformed others by showing a maximum EQE of 4.0%, which is close to the theoretical limit of fluorescent materials for a deep-blue emission (CIEy = 0.09). The same material also displayed a maximum power efficacy of 45 lm/W as a host material doped with a phosphorescent emitter Ir(ppy)3. Furthermore, the materials were also utilized as hosts with a TADF green emitter (4CzIPN) and the device based on DB34 displayed a maximum EQE of 11%, which may be attributed to the high quantum yield (69%) of the host DB34. Therefore, the bi-functional materials that are easily synthesized, economical, and possess excellent characteristics are expected to be useful in various cost-effective and high-performance OLED applications, especially in displays.

The development of solution-processable fluorescent materials with blue electroluminescence has recently attracted considerable research interest for organic light-emitting diode (OLED) applications. Whereas, conjugated polymer frameworks (CPFs) or networks (CPNs) have attained tremendous research interest due to their vast potential in a variety of cutting-edge applications including photocatalysis, sensing, gas storage, energy storage, and so on. These framework/network materials without side chains or functional groups on their backbone are generally insoluble in common organic solvents and less solution-processable for electronic device applications. Herein, we have reported two triazine-based highly fluorescent and wide-band gap donor−acceptor conjugated polymer networks (CPNs) by coupling a 3substituted thiophene (donor) unit with a triazine ring (acceptor) through a phenyl ring spacer. Two different side chains, alkyl and oligoethylene glycol, are rationally introduced into the 3-position of thiophene in the polymer network to make them solutionprocessable. Further physicochemical and optoelectronic characterizations of these emitters are performed in detail, and the effects of the side chain functionality and polarity on the above-mentioned properties are also thoroughly investigated. OLEDs based on these CPNs as emitters show a maximum external quantum efficiency of 2.3% with a maximum brightness of 2541 cd/m 2 and a maximum current efficiency of 2.8 cd/A with blue emission [Commission Internationale de l'ećlairage (CIE) coordinates of (0.17, 0.19)]. To the best of our knowledge, this may be the first example of conjugated polymer network material emitters being successfully designed, fabricated, and tested for solution-processable blue OLEDs. These results also demonstrate the high potential of the conjugated polymer network emitters for future blue or other color OLED applications.