微带型光导开关的电压转换效率

采用微带测试电路对光导开关电压转换效率进行了测试。依据传输线理论,考虑微带传输电路的端点反射,计算给出了光导开关导通电阻不为0的情况下,微带测试电路电压转换效率的解析结果。计算表明:对窄脉宽的线性电脉冲输出,电压转换效率将小于50%;对lock-on模式下的宽脉冲输出,电压转换效率可以超过50%,在理想情况下达到100%;在临界状态下,形成双峰电脉冲输出。结果表明,存在端点反射且光导开关产生电脉冲脉宽达到一定值时,微带线可以起到倍压传输线的作用。

植入式医疗设备中的电流源型无线能量传输结构

提出了一种新型的电流源型无线能量传输结构,有效提高了经皮无线能量传输的传输效率和接收端的输出电压。不同于将接收端的LC回路当作电压源的传统感应能量传输结构,提出的电流源型无线能量传输结构以一种新颖的方式,将接收端的LC回路当作电流源。这就无需在电路中使用具有部分电容和二极管的DC-DC电荷泵或者AC-DC倍压器等结构,电流源型无线能量传输结构本身就能实现具有较高电压转换效率的AC-DC转换器的功能。仿真结果表明,在1MHz的工作频率下,该结构能够实现高达±15V的直流电压输出,适用于需要高电压为20V(±10V)左右的功能性电刺激器系统。

A novel ring vibrating gyroscope based on side piezo-electrodes

Solid-state wave gyroscope is one kind of high-performance vibrating gyroscopes. The present work develops a new type of solid-state wave gyroscope—a ring vibrating gyroscope driven by piezo-electrodes located on the sidewall of the structure. It has advantages of large vibrating amplitude, high energy conversion efficiency and compact structure. The working principle of the piezoelectric ring vibrating gyroscope is based on the inertia effect of the standing wave in the axisymmetric resonator caused by Coriolis force. The finite element method(FEM) analysis has been implemented to characterize the ring type resonator. The prototypal gyroscope was manufactured and has been trimmed by mechanical way. The harmonic response of the ring vibrating gyroscope has been tested. The resonating frequency of the ring type resonator is 3715.6 Hz and the frequency split of the two working modes before trimming was about 5 Hz and was reduced to sub-0.01 Hz after trimming procedure. The Q-factor of the ring type resonator was 2504. Then, the turntable experiment was implemented. The measured scale factor k is 9.24 m V/[(°)·s] and the full scale range of the gyroscope is larger than ±300(°)/s.

Alloy-like ternary polymer solar cells with over 17.2% efficiency

Ternary strategy has been considered as an efficient method to achieve high performance polymer solar cells(PSCs). A power conversion efficiency(PCE) of 17.22% is achieved in the optimized ternary PSCs with10 wt% MF1 in acceptors. The over 8% PCE improvement by employing ternary strategy is attributed to the simultaneously increased JSCof 25.68 mA cm^-2, VOCof 0.853 V and FF of 78.61% compared with Y6 based binary PSCs. The good compatibility of MF1 and Y6 can be confirmed from Raman mapping, contact angle,cyclic voltammetry and morphology, which is the prerequisite to form alloy-like state. Electron mobility in ternary active layers strongly depends on MF1 content in acceptors due to the different lowest unoccupied molecular orbital(LUMO) levels of Y6 and MF1, which can well explain the wave-like varied FF of ternary PSCs. The third-party certified PCE of 16.8% should be one of the highest values for single bulk heterojunction PSCs. This work provides sufficient references for selecting materials to achieve efficient ternary PSCs.

CsPbBrI perovskites with low energy loss for high-performance indoor and outdoor photovoltaics

Over the years,the efficiency of inorganic perovskite solar cells(PSCs)has increased at an unprecedented pace.However,energy loss in the device has limited a further increase in efficiency and commercialization.In this work,we used(NH4)2C2O4·H2O to treat CsPbBrI2 perovskite film during spin-coating.The CsPbBrI2 underwent secondary crystallization to form high quality films with micrometer-scale and low trap density.(NH4)2C2O4·H2O treatment promoted charge transfer capacity and reduced the ideal factor.It also dropped the energy loss from 0.80 to 0.64 eV.The resulting device delivered a power conversion efficiency(PCE)of 16.55%with an open-circuit voltage(Voc)of 1.24 V,which are largely improved compared with the reference device which exhibited a PCE of 13.27%and a Voc of 1.10 V.In addition,the optimized treated device presented a record indoor PCE of 28.48%under a fluorescent lamp of 1000 lux,better than that of the reference device(19.05%).

Simulation of high conversion efficiency and open-circuit voltages of α-si/poly-silicon solar cell

The P+ α-Si /N+ polycrystalline solar cell is molded using the AMPS-1D device simulator to explore the new high efficiency thin film poly-silicon solar cell. In order to analyze the characteristics of this device and the thickness of N+ poly-silicon, we consider the impurity concentration in the N+ poly-silicon layer and the work function of transparent conductive oxide (TCO) in front contact in the calculation. The thickness of N+ poly-silicon has little impact on the device when the thickness varies from 20 μm to 300 μm. The effects of impurity concentration in polycrystalline are analyzed. The conclusion is drawn that the open-circuit voltage (Voc) of P+ α-Si /N+ polycrystalline solar cell is very high, reaching 752 mV, and the conversion efficiency reaches 9.44%. Therefore, based on the above optimum parameters the study on the device formed by P+ α-Si/N+ poly-silicon is significant in exploring the high efficiency poly-silicon solar cell.

Photo-stable perovskite solar cells with reduced interfacial recombination losses using a CeO interlayer

Despite demonstrating remarkable power conversion efficiencies(PCEs), perovskite solar cells(PSCs) have not yet achieved their full potential. In particular, the interfaces between the perovskite and charge transport layers account for the vast majority of the recombination losses.Interfacial contact and band alignment between the lowtemperature-processed TiO_(2) electron transport layer(ETL)and the perovskite are essential to minimize nonradiative recombination losses. In this study, a CeOx interlayer is employed to modify the perovskite/TiO_(2) interface, and the charge transport properties of the devices are investigated. The bilayer-structured TiO_(2)/CeOx ETL leads to the modification of the interface energetics, resulting in improved electron extraction and reduced nonradiative recombination in the PSCs.Devices based on TiO_(2)/CeOx ETL exhibit a high open-circuit voltage(Voc) of 1.13 V and an enhanced PCE of more than 20%as compared with Vocof 1.08 V and a PCE of approximately 18% for TiO^(2-)based devices. Moreover, PSCs based on TiO_(2)/CeOx ETL maintain over 88% of their initial PCEs after light illumination for 300 min, whereas PSCs based on TiO_(2) ETL almost failed. This study provides an efficient strategy to enhance the PCE and stability of PSCs based on a lowtemperature-processed TiO_(2) ETL.

Efficient organic solar cells with low-temperature in situ prepared Ga_(2)O_(3) or In_(2)O_(3) electron collection layers

Facile synthesis of an interfacial layer in organic solar cells (OSCs) is important for broadening material designs and upscaling photovoltaic conversion efficiency (PCE).Herein,a mild solution process of spin-coating In(acac)3and Ga(acac)3isopropanol precursors followed by low-temperature thermal treatment was developed to fabricate In_(2)O_(3)and Ga2O3cathode buffer layers (CBLs).The introduction of In_(2)O_(3)or Ga2O3CBLs endows PM6:Y6-based OSCs with outstanding performance and high PCEs of 16.17%and 16.01%,respectively.Comparison studies present that the In_(2)O_(3)layer possesses a work function (WF) of 4.58 eV,which is more favorable for the formation of ohmic contact compared with the Ga2O3layer with a WF of 5.06 eV and leads to a higher open circuit voltage for the former devices.Electrochemical impedance spectroscopy was performed to reveal how In_(2)O_(3)and Ga2O3affect the internal charge transfer and the origin of their performance difference.Although In_(2)O_(3)possesses lower series resistance loss,Ga2O3has a higher recombination resistance,which enhances the device fill factor and compensates for its series resistance loss to some extent.Comparative analysis of the photo-physics of In_(2)O_(3)and Ga2O3suggests that both are excellent CBLs for highly efficient OSCs.