Molecular additives are widely utilized to minimize non-radiative recombination in metal halide perovskite emitters due to their passivation effects from chemical bonds with ionic defects. However, a general and puzzling observation that can hardly be rationalized by passivation alone is that most of the molecular additives enabling high-efficiency perovskite light-emitting diodes (PeLEDs) are chelating (multidentate) molecules, while their respective monodentate counterparts receive limited attention. Here, we reveal the largely ignored yet critical role of the chelate effect on governing crystallization dynamics of perovskite emitters and mitigating trap-mediated non-radiative losses. Specifically, we discover that the chelate effect enhances lead-additive coordination affinity, enabling the formation of thermodynamically stable intermediate phases and inhibiting halide coordination-driven perovskite nucleation. The retarded perovskite nucleation and crystal growth are key to high crystal quality and thus efficient electroluminescence. Our work elucidates the full effects of molecular additives on PeLEDs by uncovering the chelate effect as an important feature within perovskite crystallization. As such, we open new prospects for the rationalized screening of highly effective molecular additives.

Thermoelectric technology can be another direct way to convert solar radiation into electricity, using the Seebeck effect. Herein, a prototype concentration solar thermoelectric generator (CTG) and a discrete numerical model for the evaluation of the whole system are presented. The model takes into account the temperature dependence of the thermoelectric material properties by dividing the thermoelectric leg into finite elements and is proved to be more accurate for calculation of the conversion efficiency of the thermoelectric modules when large temperature gradients occur in the CTG system. Based on the best available properties of various bulk thermoelectric materials reported in the literature, the best possible performance of the CTG system is predicted, and the CTG system design, including the selection of the concentration ratio and the cooling method for different thermoelectric materials, are discussed in detail.

Solution-processed perovskite light-emitting diodes (LEDs) possess outstanding optoelectronic properties for potential solid-state display applications. However, poor device stability results in significant efficiency droop partly being ascribed to Joule heating when LEDs are operated at high current densities. Herein, we used monocrystal silicon (c-Si) as the substrate and a charge injection layer to alleviate the thermal affection in perovskite LED (PeLED). By incorporating silicon oxide (SiO x ) and poly­[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-butylphenyl) (TFB) layers to tune the charge injection balance in a c-Si-based device, a PeLED achieves an external quantum efficiency of 2.12% with a current efficiency of 6.06 cd A–1. Benefiting from excellent heat dissipation of c-Si, the PeLEDs display reduced efficiency droop and extended operational lifetime. Furthermore, both electroluminescent (EL) dynamic information and static pattern displays of a c-Si-based PeLED have been successfully demonstrated. These results reveal the feasibility of potential practical c-Si-based PeLEDs with reduced efficiency droop for EL display applications.

Perovskite light‐emitting diodes (PeLEDs) have attracted both academic and industrial interest because of their high efficiency, wide color gamut as well as low material and fabrication costs. However, most state‐of‐the‐art PeLEDs are still fabricated with commonly used spin‐coating methods, which are undesirable for large‐scale commercial production. Achieving highly emissive perovskite microarrays at high spatial resolution with quick and large‐scale growth is one of the critical steps to integrate state‐of‐the‐art PeLEDs into full‐color display panels. Here, the fabrication methods and crystallization processes of perovskite materials are first discussed because they are strongly relevant to the patterning process and the quality of the perovskite pixels. Then, the current strategies to realize perovskite patterns that can be likely integrated into display panels, through mask‐free or mask‐assisted methods, are explored. Self‐emitting and down‐conversion PeLED devices with a patterned perovskite matrix as the emissive layer are also reviewed. Finally, an outlook is provided on how to further improve the optical and electrical properties of the perovskite patterns and the performance of PeLEDs as well as to develop eco‐friendly devices to accelerate the potential commercialization progress of this young technique.

Perovskite light-emitting diodes (PeLEDs) have experienced rapid improvements in the device efficiency during the last several years. However, the operational instability of PeLEDs remains a key barrier hindering their practical...