Photodetectors built from conventional bulk materials such as silicon, III-V or II-VI compound semiconductors are one of the most ubiquitous types of technology in use today. The past decade has witnessed a dramatic increase in interest in emerging photodetectors based on perovskite materials driven by the growing demands for uncooled, low-cost, lightweight, and even flexible photodetection technology. Though perovskite has good electrical and optical properties, perovskite-based photodetectors always suffer from nonideal quantum efficiency and high-power consumption. Joint manipulation of electrons and photons in perovskite photodetectors is a promising strategy to improve detection efficiency. In this review, electrical and optical characteristics of typical types of perovskite photodetectors are first summarized. Electrical manipulations of electrons in perovskite photodetectors are discussed. Then, artificial photonic nanostructures for photon manipulations are detailed to improve light absorption efficiency. By reviewing the manipulation of electrons and photons in perovskite photodetectors, this review aims to provide strategies to achieve high-performance photodetectors.

Organic diradicaloids have unique open-shell structures and properties and promising applications in organic electronics and spintronics. Incorporation of heteroatoms is an effective strategy to alter the electronic structures of organic diradicaloids. However, B-containing organic diradicaloids are very challenging due to their high reactivities, which are caused by not only diradical nature but also the B atom. In this article, we report a new kind of organic diradicaloids containing boron atoms. Our strategy is to incorporate planarized triarylboranes to antiaromatic polycyclic hydrocarbons (PHs). We synthesized two isomeric B-containing PHs composed of indenofluorene π-skeletons and two dioxa-bridged triphenylborane moieties. As proved by theoretical and experimental results, both of them have excellent ambient stability and open-shell singlet diradical structures, as well as intriguing magnetic and optoelectronic properties, such as thermally accessible triplet species, reversible multiredox ability, and narrow energy gaps. Notably, they possess sufficient Lewis acidity, which has never been observed for organic diradicaloids. In addition, they can coordinate with Lewis bases to form Lewis adducts, achieving unprecedented dynamic modulations of (anti)­aromaticity and thus diradical character of organic diradicaloids.

Heterocyclic diradicaloids with atom‐precise control over open‐shell nature are promising materials for organic electronics and spintronics. Herein, we disclose quinoidal π‐extension of a B/N‐heterocycle for generating B/N‐type organic diradicaloids. Two quinoidal π‐extended B/N‐doped polycyclic hydrocarbons that feature fusion of the B/N‐heterocycle motif with the antiaromatic s‐indacene or dicyclopenta[b,g]naphthalene core were synthesized. This quinoidal π‐extension and B/N‐heterocycle leads to their open‐shell electronic nature, which stands in contrast to the multiple‐resonance effect of conventional B/N‐type emitters. These B/N‐type diradicaloids have modulated (anti)aromaticity and enhanced diradical characters comparing with the all‐carbon analogues, as well as intriguing properties, such as magnetic activities, narrow energy gaps and highly red‐shifted absorptions. This study thus opens the new space for both of B/N‐doped polycyclic π‐systems and heterocyclic diradicaloids.

This review focuses on the existing strategies and underlying mechanisms, and discusses future directions in epitaxial substrate engineering to deliver wafer-scale 2D materials for integrated electronics and photonics.

Single‐photon detectors (SPDs) that can sense individual photons are the most sensitive instruments for photodetection. Established SPDs such as conventional silicon or III–V compound semiconductor avalanche diodes and photomultiplier tubes have been used in a wide range of time‐correlated photon‐counting applications, including quantum information technologies, in vivo biomedical imaging, time‐of‐flight 3D scanners, and deep‐space optical communications. However, further development of these fields requires more sophisticated detectors with high detection efficiency, fast response, and photon‐number‐resolving ability, etc. Thereby, significant efforts have been made to improve the performance of conventional SPDs and to develop new photon‐counting technologies. In this review, the working mechanisms and key performance metrics of conventional SPDs are first summarized. Then emerging photon‐counting detectors (in the visible to infrared range) based on 0D quantum dots, 1D quantum nanowires, and 2D layered materials are discussed. These low‐dimensional materials exhibit many exotic properties due to the quantum confinement effect. And photodetectors built from these nD‐materials (n = 0, 1, 2) can potentially be used for ultra‐weak light detection. By reviewing the status and discussing the challenges faced by SPDs, this review aims to provide future perspectives on the research directions of emerging photon‐counting technologies.

Hot carrier harvest could save 30% energy loss in solar cells. So far, however, it is still unreachable as the photoexcited hot carriers are short-lived, ∼1 ps, determined by a rapid relaxation process, thus invalidating any reprocessing efforts. Here, we propose and demonstrate a feasible route to reserve hot electrons for efficient collection. It is accomplished by an intentional mix of cubic zinc-blend and hexagonal wurtzite phases in III−V semiconductor nanowires. Additional energy levels are then generated above the conduction band minimum, capturing and storing hot electrons before they cool down to the band edges. We also show the superiority of core/shell nanowire (radial heterostructure) in extracting hot electrons. The strategy disclosed here may offer a unique opportunity to modulate hot carriers for efficient solar energy harvest.

Tuning diradical character is an important topic for organic diradicaloids. Herein, we report the precise borylation enabling structural isomerism as an effective strategy to modulate diradical character and thereby properties of organic diradicaloids. We synthesized a new B‐containing polycyclic hydrocarbon that has the indeno[1,2‐b]fluorene π‐skeleton with the β‐carbons bonding to two boron atoms. Detailed theoretical and experimental results show that this bonding pattern leads to its distinctive electronic structures and properties in comparison to that of its isomeric molecule. This molecule has the efficient conjugation between boron atoms and π‐skeleton, resulting in downshifted LUMO and HOMO levels. Moreover, it exhibits smaller diradical character and thereby inhibited diradical properties, such as significantly blue‐shifted light absorption, larger energy bandgap and weak para‐magnetic resonance. Notably, this B‐containing polycyclic hydrocarbon possesses much stronger Lewis acidity and its Lewis acid‐base adducts display enhanced diradical character, demonstrating the positive effects of Lewis coordination on modulating diradical performance.

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