Carbon-based nanomaterials hold promise for eco-friendly alternatives to heavy-metal-containing quantum dots (QDs) in optoelectronic applications. Here, boric acid-functionalized graphene quantum dots (B-GQDs) were prepared using bottom-up molecular fusion based on nitrated pyrenes and boric acid. Such B-GQDs with crystalline graphitic structures and hydrogenbonding functionalities would be suitable model systems for unraveling the photoluminescence (PL) mechanism, while serving as versatile building blocks for supramolecular self-assembly. Unlike conventional GQDs with multiple emissive states, the B-GQDs exhibited excitation-wavelength-independent, vibroniccoupled excitonic emission. Interestingly, their PL spectra can be tuned without largely sacrificing the quantum yield (QY) due to two-dimensional self-assembly. In addition, such B-GQDs in a polystyrene matrix possessed an ultrahigh QY (∼90%) and large exciton binding energy (∼300 meV). Benefiting from broadband absorption, ultrahigh QY, and long-wavelength emission, efficient laminated luminescent solar concentrators (100 × 100 × 6.3 mm 3 ) were fabricated, yielding a high power conversion efficiency (1.4%).

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The booming growth in environmental conditions sensing and monitoring pushes the need of inexpensive environment sensors with small size and low power consumption. The outbreak of COVID-19 further increases the need for fast monitoring of environment conditions. The micro-electrical-mechanical-systems (MEMS) technologies are considered as promising solutions to realize the required environment sensors. The mature complementary metal-oxide-semiconductor (CMOS) process platforms available in many foundries can be extended to fabricate MEMS sensors to offer the advantage of relatively easier commercialization. Moreover, by leveraging the characteristics of CMOS process platforms, the integration of multiple sensors and sensing circuits to form a compact sensing system can also be achieved. This review paper will focus on introducing the miniaturized environmental sensing devices implemented and integrated using the CMOS-MEMS technologies. In general, the CMOS chips for environment sensing are firstly fabricated using the foundry-available CMOS processes, and then the post-CMOS micromachining processes are performed to implement the CMOS-MEMS environment sensors. This paper respectively reviews five different environment sensors (including the infrared, pressure (barometer), humidity/temperature, and gas sensors) using the CMOS-based MEMS technologies. The advantages and design concerns of sensors fabricated by different CMOS and post-CMOS processes are introduced and discussed. Moreover, the CMOS-MEMS environment sensing hub implemented through the monolithic integration of multiple environment sensors is also introduced.

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