Realizing over 10% efficiency in polymer solar cell by device optimization

The low band gap polymer based on benzodithiophene(BDT)-thieno[3,4-b]thiophene(TT)backbone,PBDT-TS1,was synthesized following our previous work and the bulk heterojunction(BHJ)material comprising PBDT-TS1/PC71BM was optimized and characterized.By processing the active layer with different additives i.e.1,8-diiodooctane(DIO),1-chloronaphthalene(CN)and 1,8-octanedithiol(ODT)and optimizing the ratio of each additive in the host solvent,a high PCE of 9.98%was obtained under the condition of utilizing 3%DIO as processing additive in CB.The effect of varied additives on photovoltaic performance was illustrated with atomic force microscopy(AFM)and transmission electron microscope(TEM)measurements that explained changes in photovoltaic parameters.These results provide valuable information of solvent additive choice in device optimization of PBDTTT polymers,and the systematic device optimization could be applied in other efficient photovoltaic polymers.Apparently,this work presents a great advance in single junction PSCs,especially in PSCs with conventional architecture.

Modeling and optimization of a multi-carrier renewable energy system for zero-energy consumption buildings

For the carbon-neutral,a multi-carrier renewable energy system(MRES),driven by the wind,solar and geothermal,was considered as an effective solution to mitigate CO2emissions and reduce energy usage in the building sector.A proper sizing method was essential for achieving the desired 100%renewable energy system of resources.This paper presented a bi-objective optimization formulation for sizing the MRES using a constrained genetic algorithm(GA)coupled with the loss of power supply probability(LPSP)method to achieve the minimal cost of the system and the reliability of the system to the load real time requirement.An optimization App has been developed in MATLAB environment to offer a user-friendly interface and output the optimized design parameters when given the load demand.A case study of a swimming pool building was used to demonstrate the process of the proposed design method.Compared to the conventional distributed energy system,the MRES is feasible with a lower annual total cost(ATC).Additionally,the ATC decreases as the power supply reliability of the renewable system decreases.There is a decrease of 24%of the annual total cost when the power supply probability is equal to 8%compared to the baseline case with 0%power supply probability.

A charge allocating model for the breakdown voltage calculation and optimization of the lateral RESURF devices

A new quite simple analytical model based on the charge allocating approach has been proposed to describe the breakdown property of the RESURF （reduced surface field） structure. It agrees well with the results of numerical simulation on predicting the breakdown voltage. Compared with the latest published analytical model, this model has a better accuracy according to the numerical simulation with simpler form. The optimal doping concentration （per unit area） of the epi-layer of the RESURF structures with different structure parameters has been calculated based on this model and the results show no significant discrepancy to the data gained by others. Additionally the physical mechanism of how the surface field is reduced is clearly illustrated by this model.

Designerly optimization of devices(as reflectors)to improve daylight and scrutiny of the light-well’s configuration

One of the most effective ways of transmitting daylight into deep-plan buildings is to generate light-well for spaces away from the facade and window-less spaces.Among the limited methods of improving daylight efficiency in light-wells are reflectors that,as a surplus member of the wells,can aid in this improvement.A scrutiny of the light-well’s configuration can give a correct perception of the performance of the well’s walls with increasing the reflection coefficient to the designers in deciding where to install the openings,selecting the transmittance coefficient of glass,etc.In this paper,the main focus is designing and optimizing daylight assist devices on light-wells that can hierarchically reflect light from the sky to the bottom of the well(Device 1)and then emit into the desired space(Device 2).The research highlights that it is necessary to find a proper strategy for the devices regarding to the optimization process.The research design results in a comprehensive standard solution for different latitudes.The simulations were performed by Honeybee Plus version 0.0.06 and Honeybee-Ladybug version 0.0.69-0.0.66,which has the ability to simulate annual daylight performance at certain periods.Due to the maximum and minimum altitudes at any latitude,the study required time-criteria throughout the year.As a result,a cross-sectional study was carried out at two critical times:the first period(P1)and the second period(P2).Daylight metrics for analyzing configuration as well as evaluating devices are E’max,avg(illumination)and SHA(hour/m2).The DA’300 and DA’max2000 metrics were selected to measure daylight efficiency and glare risk,respectively,and the sDA is for the amount of floor area that uses enough daylight.Also,to better percept how to prepare improved-daylight at lower levels(especially for the performance of devices),the daylight autonomy has been reduced from 50%to 40%and a metric such as sDA’t40 has been created.

Optimal placement of dampers and actuators based on stochastic approach

A general method is developed for optimal application of dampers and actuators by installing them at optimal location on seismic-resistant structures.The study includes development of a statistical criterion,formulation of a general optimization problem and establishment of a solution procedure.Numerical analysis of the seismic response in time-history of controlled structures is used to verify the proposed method for optimal device application and to demonstrate the effectiveness of seismic response control with optimal device location.This study shows that the proposed method for the optimal device application is simple and general,and that the optimally applied dampers and actuators are very efficient for seismic response reduction.

Optimizing Device Implantation in Patients with Atrial Fibrillation and Risk of Stroke

According to clinical studies,about a third of patients with atrial fibrillation will suffer a stroke during their lifetime.Between 70 and 90%of these strokes are caused by a thrombus formed in the left atrial appendage.The study was to develop tools based on biophysical models and interactive interfaces to optimize LAAO device therapies.

Effects of spin-coating speed on the morphology and photovoltaic performance of the diketopyrrolopyrrole-based terpolymer

Polymer solar cells(PSCs) were fabricated by combining a diketopyrrolopyrrole-based terpolymer(PTBT-HTID-DPP) as the electron donor, and [6,6]-phenyl C_(61) butyric acid methyl ester(PC_(61)BM) as the electron acceptor, and the power conversion efficiency(PCE) of 4.31% has been achieved under AM 1.5 G(100 m W cm^(-2)) illumination condition via optimizing the polymer/PC_(61)BM ratio, the variety of solvent and the spin-coating speed. The impact of the spin-coating speed on the photovoltaic performance of the PSCs has been investigated by revealing the effects of the spin-coating speed on the morphology and the absorption spectra of the polymer/PC_(61)BM blend films. When the thickness of the blend films are adjusted by spin-coating a fixed concentration with different spin-coating speeds, the blend film prepared at a lower spin-coating speed shows a stronger absorption per unit thickness, and the correspond device shows higher IPCE value in the longer-wavelength region. Under the conditions of similar thickness, the blend film prepared at a lower spin-coating speed forms a more uniform microphase separation and smaller domain size which leads to a higher absorption intensity per unit thickness of the blend film in long wavenumber band, a larger short-circuit current density(J_(sc)) and a higher power conversion efficiency(PCE) of the PSC device. Noteworthily, it was found that spin-coating speed is not only a way to control the thickness of active layer but also an influencing factor on morphology and photovoltaic performance for the diketopyrrolopyrrole-based terpolymer.

Threshold voltage adjustment of organic thin film transistor by introducing a polysilicon floating gate

The structure of organic thin film transistors （OTFTs） is optimized by introducing a floating gate into the gate dielectric to reduce the threshold voltage of OTFTs. Then the optimized device is simulated, and the simulation results show that the threshold voltage of optimized device is reduced by about 10 V. The reduction of the threshold voltage is helpful and useful for the application of OTFTs in many areas. In addition, this way of reducing the threshold voltage of OTFT is compatible with traditional silicon technology and can be used in manufacturing.