Mechanoluminescence (ML), a novel process that converts mechanical momentum to light emission, has shown potential for sustainable future technologies. However, the lights emitted from classical ML materials have shown broad emission spectra and the limitation in the choice of colors so far, constraining the full-color implementation of ML. Herein, a quantum dot (QD)-in-mechanoluminescent matrix (QMM) architecture is introduced by simply incorporating QDs with the classical ML-active matrices, designed to utilize the sharp emission spectra of the QDs. The QMMs demonstrate distinctive green and red lights identical to the emissions from the QDs through mechanical stimuli, achieving the purest ML reported to date. Furthermore, the deployments of the QDs allow the full-color implementation of ML covering a wide color gamut, as well as the demonstration of the purest white reported to date. Systematic investigations reveal that the ML operation in the QMM is governed according to the ML-stimulated PL mechanism, preventing energy or charge transfer processes. Moreover, the QMMs exhibit excellent stabilities upon environmental stresses and the patterned system is readily prepared, guaranteeing both robustness and easy processability of the system. This simple QMM strategy suggests practical insights for the development of powerless ML display and lighting systems.
이 연구의 목적은 소조사면 선량계측을 위하여 엣지검출기의 성능을 평가하기 위함이다. 다양한 소조사면과 깊이에서 엣지검출기(Model 1118 Edge)를 이용하여 6 MV 광자선의 선량 직선성, 선량률 의존도, 출력 계수, 선량 측면도 및 심부선량 백분율을 따라 측정하였으며, 이를 표준용적의 이온전리함(CC13)과 광자선 다이오드 검출기(PFD)와 비교하였다. 선량 직선성을 일차 선형 맞춤 함수와 비교하였을 때, 세 검출기 모두 1% 미만의 차이를 나타냈으며, 엣지검출기는 -0.08~0.08%의 가장 낮은 차이를 보였다. 선량율의 변화(100~600 MU/min)에 따라 PFD와 엣지검출기의 정규화된 반응비는 1% 미만의 일정한 값을 보였으나, CC13은 100 MU/min에서 약 -5%의 변화를 나타냈다. 조사면의 크기( $4{\times}4\;cm^2{\sim}10{\times}10\;cm^2$ )에 따른 출력계수는 세 검출기 모두 거의 같은 값을 보였으나, $4{\times}4\;cm^2$ 이하의 소조사면에서는 엣지검출기와 PFD의 출력 계수가 CC13과 최대 21%의 차이보였다. 각 조사면에서 20~80%의 반음영 폭을 측정하였을 때, 평균적으로 CC13은 엣지검출기보다 2배, PFD는 약 30% 정도 더 넓게 나타났다. 또한 10~90%의 반음영의 경우, CC13과 PFD가 각각 55%와 19% 정도 더 넓은 폭을 나타냈다. 엣지검출기는 선량 측면도의 반치폭이 조사면의 크기와 거의 일치하였으나, 다른 두 검출기는 조사면의 크기보다 약 8~10% 더 크게 나타났으며, 심부선량백분율은 각 조사면에서 세 검출기 모두 거의 일치하였다. 엣지검출기의 성능평가를 위한 선량특성을 분석한 결과, $4{\times}4\;cm^2$ 이하의 소조사면에서 가장 적합한 특성을 나타냈으며, CC13과 PFD와 같은 검출기는 조사면이 작을수록 상당한 오차를 나타낼 수 있음을 알 수 있었다. 【In this study, we evaluated an edge detector for small-beam dosimetry. We measured the dose linearity, dose rate dependence, output factor, beam profiles, and percentage depth dose using an edge detector (Model 1118 Edge) for 6-MV photon beams at different field sizes and depths. The obtained values were compared with those obtained using a standard volume ionization chamber (CC13) and photon diode detector (PFD). The dose linearity results for the three detectors showed good agreement within 1%. The edge detector had the best linearity of ${\pm}0.08%$ . The edge detector and PFD showed little dose rate dependency throughout the range of 100~600 MU/min, while CC13 showed a significant discrepancy of approximately -5% at 100 MU/min. The output factors of the three detectors showed good agreement within 1% for the tested field sizes. However, the output factor of CC13 compared to the other two detectors had a maximum difference of 21% for small field sizes ( ${\sim}4{\times}4\;cm^2$ ). When analyzing the 20~80% penumbra, the penumbra measured using CC13 was approximately two times wider than that using the edge detector for all field sizes. The width measured using PFD was approximately 30% wider for all field sizes. Compared to the edge detector, the 10~90% penumbras measured using the CC13 and PFD were approximately 55% and 19% wider, respectively. The full width at half maximum (FWHM) of the edge detector was close to the real field size, while the other two detectors measured values that were 8~10% greater for all field sizes. Percentage depth doses measured by the three detectors corresponded to each other for small beams. Based on the results, we consider the edge detector as an appropriate small-beam detector, while CC13 and PFD can lead to some errors when used for small beam fields under $4{\times}4\;cm^2$ .】
Here, we demonstrate a new synthetic strategy for converting low-energy benzo[c][1,2,5]thiadiazole (BT)-based polymers into efficient polymeric donors for non-fullerene acceptor-based organic solar cells (NFA–OSCs). A highly planar 5,6-difluoro-benzo[c][1,2,5]thiadiazole (ffBT)-based alternating polymer, P1, comprising electron-rich 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene (BDTT) and strong electron-deficient 5,6-difluoro-4,7-bis(4-octylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (DTffBT) units is prepared. Additionally, two ternary polymers, P2 and P3, are prepared by replacing 25% and 50% of the DTffBT unit on the P1 backbone with a weak electron-deficient 2,5-dioctyl-4,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione (DTPPD) unit, which has a twisted but well-controlled wavy backbone. The properties of the resulting polymers, P1–P3, are investigated to understand the effects of changing the planarity and curvature of the backbone of the BT-based polymers. Notably, increasing the concentration of the DTPPD unit on P1 results in a blue-shift in absorption band and relatively deep energy levels. Further, the absorption and X-ray diffraction (XRD) spectra of the polymers confirm that the π–π stacking of the polymers is decreased by increasing the amount of DTPPD units on P1. The NFA–OSCs fabricated using P1–P3 as the electron donor and ITIC as the electron acceptor afford maximum power conversion efficiencies ( PCE ) of 3.22%, 3.99%, and 5.16%. The PCE is further improved to 2.46%, 4.52%, and 7.54%, respectively, using Y6 instead of ITIC. Overall, the photovoltaic performance of the BT-based polymers is significantly improved from 2.46% to 7.54% by lowering their planarity and/or changing their backbone curvature.
The effect of various electron pressure models on the debris-ambient coupling in a magnetized collisionless shock is demonstrated with a 2-D hybrid code. The simulation specifically models the regime of laboratory shocks launched by laser ablation into a magnetized ambient plasma. A two-electron-fluid model is employed with different polytropic coefficients to vary the electron temperature and pressure gradients and investigate their effects on the shock dynamics, the electric field, and the coupling between debris and ambient ions. The simulations show a significant variation in the radial electric field and ion dynamics with the polytropic index.
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