Semitransparent organic solar cells with high light utilization efficiency and color rendering index

Semitransparent organic solar cells(ST-OSCs)have garnered considerable attention as promising renewable energy technology for integrating photovoltaics into buildings.However,there is a trade-off between power conversion efficiency(PCE)and average visible transmittance(AVT),which hinders the achievement of a high light utilization efficiency(LUE).In this study,we propose a valuable method to address this challenge by replacing the transparent top electrode,Ag,with a 20 nm layer of Au.The ST-OSCs based on the 20 nm Au electrode demonstrate superior exciton extraction,more efficient charge collection,and higher color-rendering index(CRI)due to their smoother surface,higher conductivity,and enhanced visible light transmittance,resulting in a significantly higher PCE of 13.67%and an enhanced AVT of 30.17%,contributing to a high LUE of 4.15%.Additionally,optically transparent dielectric layers,applied on the front and back sides of the ST-OSCs to further boost performance,delivered an impressive LUE of 4.93%,with PCE and AVT values reaching 14.44%and 34.12%,respectively.Notably,the champion ST-OSCs also exhibited a favorable CRI value of 93.37.These achievements represent the bestperforming ST-OSCs to date with both high LUE and CRI and hold significant implications for the prospective commercialization of ST-OSCs.

18.01%Efficiency organic solar cell and 2.53%light utilization efficiency semitransparent organic solar cell enabled by optimizing PM6:Y6 active layer morphology

Optimizing the photoactive layer morphology is a simple,promising way to improve the power conversion efficiencies(PCEs)of organic solar cells(OSCs).Here,we compared different post-processing treatments on PM6:Y6 blend films and relevant effects on device performances,including as-cast,thermal annealing and solvent annealing.This solvent annealing processes can effectively improve the vertical distribution and aggregation of polymer donors and small molecule acceptors,then optimize the active layer film morphology,ultimately elevating PCE.Thus,one of champion efficiencies of 18.01%was achieved based on the PM6:Y6 binary OSCs.In addition,a relatively high light utilization efficiency(2.53%)was achieved when a transparent electrode made of Cu(1 nm)and Ag(15 nm)was utilized to fabricate a semitransparent OSC with a remarkable PCE of 13.07%and 19.33%average visible-light transmittance.These results demonstrated that carefully optimizing morphology of active layer is conducive to achieving a high-performance OSC.

Characteristics of Light Availability Under Forest Canopies and Its Influences on Photosynthesis of Understory Plants

Available light under forest canopies includes two components, diffuse light and direct light (sunflecks), and is characterized as low and highly dynamic. Understory habitats under different forest types experience different light conditions. Sunflecks as a critical resource for understory plants have great importance on carbon gain of understory plants. Under the light-limiting habitat, understory plants exhibit a high light utilization efficiency attributed by a post-illumination CO2 uptake. Although different species have different photosynthetic responses, shade plants appear to be acclimated to respond more quickly and efficiently to sunflecks. This acclimation includes a faster induction, relatively lower rate of induction loss, lower photosynthetic compensation point, and higher water use efficiency. The process that shade plants harvest light energy is not well known. Studies of photosynthetic responses to sunflecks in natural conditions are rare. Little is known about constraints on sunfleck utilization, which may change seasonally. Extensive field studies in conjunction with laboratory investigations will be needed to further understand potential and actual constraints on sunfleck utilization. Most studies on photosynthetic responses to fluctuating light condition were done in the level of leaves. Fluctuating light utilization on the basis of whole plants and populations presents future challenges to ecologists.

Estimation of Net Primary Productivity of Terrestrial Vegetation in China by Remote Sensing

Among the many approaches for studying the net primary productivity (NPP), a new method by using remote sensing was introduced in this paper. With spectral information source (the visible band, near infrared band and thermal infrared band) of NOAA-AVHRR, we can get the relative index and parameters, which can be used for estimating NPP of terrestrial vegetation. By means of remote sensing, the estimation of biomass and NPP is mainly based on the models of light energy utilization. In other words, the biomass and NPP can be calculated from the relation among NPP, absorbed photosynthetical active radiation (APAR) and the rate (epsilon) of transformation of APAR to organic matter, thus: NPP = ( FPAR x PAR) x [epsilon * x sigma (T) x sigma (E) x sigma (S) x (1 - Y-m) x (1 - Y-g)]. Based upon remote sensing ( RS) and geographic information system (GIS), the NPP of terrestrial vegetation in China in every ten days was calculated, and the annual NPP was integrated. The result showed that the total NPP of terrestrial vegetation in China was 6.13 x 10(9) t C . a(-1) in 1990 and the maximum NPP was 1 812.9 g C/m(2). According to this result, the spatio-temporal distribution of NPP was analyzed. Comparing to the statistical models, the RS model, using area object other than point one, can better reflect the distribution of NPP, and match the geographic distribution of vegetation in China.

MISO visible light communication system utilizing hybrid post-equalizer aided pre-convergence of STBC decoding

In this Letter, we propose a modified hybrid linear and nonlinear post-equalizer to aid pre-convergence of space–time block coding（STBC） decoding in the formulated multiple-input-single-output（MISO） visible light communication（VLC） model. Meanwhile, we present a channel estimation algorithm, as the existing method is suboptimal. Experiments demonstrate that a data rate of 1 Gbit/s is easily achieved in 1.3 m indoor free space transmission with the bit error rate（BER） limited to 3.8 × 10^-3. Correspondingly, the Q factor can be improved to 3.13 d B compared to the pure linear equalizer case.

CW blue light generation at 429 nm by utilizing second harmonic process with KNbO_3

Continuous-wave blue light at 429 nm from a second harmonic process has been investigated at room temperature with Potassium Niobate (KNbO3) crystal. Optimum parameters for nonlinear conversion in our designing single-resonant, external ring cavity pumped by the Ti:sapphire laser are established. 39% of maximum overall conversion efficiency is obtained and factors that limit the conversion efficiency is discussed.

Recent progress on advanced design for photoelectrochemical reduction of CO_2 to fuels

The energy crisis and global warming become severe issues. Solar-driven CO2 reduction provides a promising route to confront the predicaments, which has received much attention. The photoelectrochemical（PEC） process,which can integrate the merits of both photocatalysis and electrocatalysis, boosts splendid talent for CO2 reduction with high efficiency and excellent selectivity. Recent several decades have witnessed the overwhelming development of PEC CO2 reduction. In this review, we attempt to systematically summarize the recent advanced design for PEC CO2 reduction. On account of basic principles and evaluation parameters, we firstly highlight the subtle construction for photocathodes to enhance the efficiency and selectivity of CO2 reduction, which includes the strategies for improving light utilization, supplying catalytic active sites and steering reaction pathway.Furthermore, diversiform novel PEC setups are also outlined.These exploited setups endow a bright window to surmount the intrinsic disadvantages of photocathode, showing promising potentials for future applications. Finally, we underline the challenges and key factors for the further development of PEC CO2 reduction that would enable more efficient designs for setups and deepen systematic understanding for mechanisms.