A ZnS/CaZnOS Heterojunction for Efficient Mechanical‐to‐Optical Energy Conversion by Conduction Band Offset

Abstract

heterojunctions have been constructed and demonstrated for controlling optical, [1] electrical, [2] mechanical [3] and magnetic characteristics. [4] In particular, semiconductor heterojunctions as the core of light-emitting diodes (LEDs) have played vital roles in electric-driven lighting and display devices. The electric potential of a semiconductor heterojunction has a strong positive effect on charge carrier transport at the interface and can tune/ control the behaviors of light emitting. [5] The advances in lighting technology have greatly promoted the development of artificial intelligence, biotechnology and flexible optoelectronics. [6] At present, almost all LEDs are driven by external power supply through wire connecting electrodes. However, the high-efficiency heterojunction material driven by Newton force to achieve the stress light-emitting devices is still limited in the present research. Thus, the exploration of such a new type of light-emitting device without wires and electrodes not only supplies advanced heterojunction systems for light-emitting but also provides a prospective reference for the future multiapproach energy conversion with extended applications.As a special type of light source, mechanoluminescence (ML) materials are capable of generating photon emissions in response to mechanical stimuli. In comparison with LEDs based on electroluminescence (EL), ML provides sustainable light output by excitation of mechanical energy ubiquitously available in nature. During the past decade, ML materials have attracted widespread interests due to their promising applications in stress sensing, display, artificial skin, bioimaging, anti-counterfeiting, structure fatigue diagnosis, night surveillance and flexible optoelectronics. [7][8][9][10] However, the recent developments of highperformance ML materials are not as fast as other luminescence systems such as photoluminescence (PL)/EL, which is attributed to the lack of rational design of ML material systems guided by the in-depth theoretical exploration in the mechanism. ML materials known to date are typically homogenous structures, which offer limited space for optimizing the ML performance. Therefore, further improving the ML performance by exploiting heterostructures remains a challenge for present research. [11,12] In this work, we fabricate a class of ZnS/CaZnOS heterostructures, which flexibly tune the efficient and reproducible Actively collecting the mechanical energy by efficient conversion to other forms of energy such as light opens a new possibility of energy-saving, which is of pivotal significance for supplying potential solutions for the present energy crisis. Such energy conversion has shown promising applications in modern sensors, actuators, and energy harvesting. However, the implementation of such technologies is being hindered because most luminescent materials show weak and non-recoverable emissions under mechanical excitation. Herein, a new class of heterojunctioned ZnS/CaZnOS piezophotonic systems is presented, which disp...

Luminescence in Manganese (II)-Doped SrZn2S2O Crystals From Multiple Energy Conversion

“…Among these, some typical oxysulfides notably enriched the color of ML emission due to its good acceptance for a large number of activators (Zhang et al, 2013 , 2015 ). It is proved that some new oxysulfide semiconductors that doped with luminescent ions, for instance, transitional metals and lanthanide ions doped CaZnOS (Huang, 2016 ; Huang et al, 2017 ; Du et al, 2019 ), SrZnOS (Chen et al, 2020 ), and BaZnOS (Li et al, 2016 ) single compounds as well as CaZnOS-ZnS heterojunctions (Peng et al, 2020 ) show novel ML performances that result in diverse applications. Meanwhile, some oxysulfides, such as Gd 2 O 2 S-based luminescent material (Büchele et al, 2015 ), has been commercialized and confirmed to be good X-ray phosphors.…”

Remote Regulation of Optogenetic Proteins by a Magneto‐Luminescence Microdevice

“…[ 16 ] In order to achieve continuous optogenetic stimulation, lanthanide‐doped CaZnOS crystals were selected as the candidate materials, which could generate sustainable ML through a piezophotonic effect, in which the photonic excitation was established by mechanically induced tribo/piezoelectric potential in the CaZnOS ( Figure a,b). [ 17 ] As an added benefit, the CaZnOS crystals can host a variety of dopants, such as manganese and lanthanides, for the delivery of tunable ML spectra (Figure 1b). The excitation energy was extracted by dopant ions in the CaZnOS host, wherein characteristic emission peaks at different wavelengths were generated (Figure 1c; Figure S1d, Supporting Information).…”

Near-infrared mechanoluminescence crystals: a review

“…Interestingly, in 2020, Peng et al.’s research work has reached this goal to some extent. Herein, a new class of heterojunctioned ZnS/CaZnOS piezophotonic system with remarkable ML performance in both intensity and reproducibility was demonstrated ( Figure 4 ) ( Peng et al., 2020 ). ZnS and CaZnOS were prepared by controlling the ratio of CaCO 3 and ZnS, and they accommodate Mn 2+ and lanthanide ions (such as Tm 3+ , Yb 3+ , and Pr 3+ NIR luminescent ions), respectively.…”

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Figure 4 Scheme of proposed mechanism for mechanical-to-optical energy conversion in the piezophotonic semiconductor heterojunction Scheme of proposed mechanism for mechanical-to-optical energy conversion in the piezophotonic semiconductor heterojunction: electronic transition in the ML process is facilitated by band offsets at the heterojunction interface region (indicated by the red frame). Reproduced with permission from ( Peng et al., 2020 ). Copyright 2020 WILEY.

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