There has been a strong interest in the use of Phase Change Materials (PCMs) for the transient thermal abatement of high powered microprocessor.This paper presents a set of transient computational analysis for selecte...There has been a strong interest in the use of Phase Change Materials (PCMs) for the transient thermal abatement of high powered microprocessor.This paper presents a set of transient computational analysis for selected IC packages with the purpose of calibrating the merits of PCM in different configurations.The transient analysis of high powered microprocessors with heat sinks was performed as a benchmark for comparison with the same microprocessors fitted with PCM in the following configurations:a) PCM imbedded into the finned region of the heat sink,b) PCM mounted between the microprocessor and heat sink,c) sealed PCM underfill to the microprocessor and d) PCM fitted to the underside of the printed circuit board directly beneath the microprocessor.The analysis was performed using a commercial CFD tool together with an approximation to the phase change mechanism using the slope method.Results indicate the merit of each configuration.展开更多
We have researched the performances of organic photovoltaic devices with the bulk heterojunction （BHJ） structure using the organic solution-processable functionalized graphene （SPFGraphene） material as the electro...We have researched the performances of organic photovoltaic devices with the bulk heterojunction （BHJ） structure using the organic solution-processable functionalized graphene （SPFGraphene） material as the electron-accepter material and P3OT as the donor material. The structural configuration of the device is ITO/PEDOT：PSS/P3OT：PCBM-SPFGraphene/LiF/A1. Given the P3OT/PCBM （1：1） mixture with 8wt% of SPFGraphene, the open-circuit voltage （Voc） of the device reaches 0.64 V, a short-circuit current density （J^c） reaches 5.7 mA/cm2, a fill factor （FF） reaches 0.42, and the power conversion efficiency （7？） reaches 1.53% at illumination at 100 mW/cm2 AM1.5. We further studied the reason for the device performances improvement In the P3OT：PCBM-SPFGraphene composite, the SPFGraphene material acts as exciton dissociation sites and provides the transport pathways of the lowest unoccupied molecular orbital （LUMO）-SPFGraphene-A1. Furthermore, adding SPFGraphene to P3OT results in appropriate energetic distance between the highest occupied molecular orbital （HOMO） and LUMO of the donoffacceptor and provides higher exciton dissociation volume mobility of carrier transport. We have researched the effect of annealing treatment for the devices and found that the devices with annealing treatment at 180℃ show better performances compared with devices without annealed treatment. The devices with annealed treatment show the best performance, with an enhancement of the power conversion efficiency from 1.53% to 1.75%.展开更多
文摘There has been a strong interest in the use of Phase Change Materials (PCMs) for the transient thermal abatement of high powered microprocessor.This paper presents a set of transient computational analysis for selected IC packages with the purpose of calibrating the merits of PCM in different configurations.The transient analysis of high powered microprocessors with heat sinks was performed as a benchmark for comparison with the same microprocessors fitted with PCM in the following configurations:a) PCM imbedded into the finned region of the heat sink,b) PCM mounted between the microprocessor and heat sink,c) sealed PCM underfill to the microprocessor and d) PCM fitted to the underside of the printed circuit board directly beneath the microprocessor.The analysis was performed using a commercial CFD tool together with an approximation to the phase change mechanism using the slope method.Results indicate the merit of each configuration.
基金supported by the National Outstanding Youth Science Foundation (Grant No. 60825407)the National Basic Research Program of China (Grant Nos. 2011CB932700 and 2011CB932703)+3 种基金the National Natural Science Foundation of China (Grant Nos. 60877025 and61077044)Beijing Science and Technology Committee (Grant Nos.Z101103055810003 and D090803044009001)Beijing Natural Science Fund Project (Grant No. 2092024)the Excellent Doctor’s Science and Technology Innovation Foundation of Beijing Jiaotong University, China(Grant No. 2011YJS279)
文摘We have researched the performances of organic photovoltaic devices with the bulk heterojunction （BHJ） structure using the organic solution-processable functionalized graphene （SPFGraphene） material as the electron-accepter material and P3OT as the donor material. The structural configuration of the device is ITO/PEDOT：PSS/P3OT：PCBM-SPFGraphene/LiF/A1. Given the P3OT/PCBM （1：1） mixture with 8wt% of SPFGraphene, the open-circuit voltage （Voc） of the device reaches 0.64 V, a short-circuit current density （J^c） reaches 5.7 mA/cm2, a fill factor （FF） reaches 0.42, and the power conversion efficiency （7？） reaches 1.53% at illumination at 100 mW/cm2 AM1.5. We further studied the reason for the device performances improvement In the P3OT：PCBM-SPFGraphene composite, the SPFGraphene material acts as exciton dissociation sites and provides the transport pathways of the lowest unoccupied molecular orbital （LUMO）-SPFGraphene-A1. Furthermore, adding SPFGraphene to P3OT results in appropriate energetic distance between the highest occupied molecular orbital （HOMO） and LUMO of the donoffacceptor and provides higher exciton dissociation volume mobility of carrier transport. We have researched the effect of annealing treatment for the devices and found that the devices with annealing treatment at 180℃ show better performances compared with devices without annealed treatment. The devices with annealed treatment show the best performance, with an enhancement of the power conversion efficiency from 1.53% to 1.75%.
