Performance enhancement of ZnO nanowires/PbS quantum dot depleted bulk heterojunction solar cells with an ultrathin Al_2O_3 interlayer

Depleted bulk heterojunction(DBH)PbS quantum dot solar cells(QDSCs),appearing with boosted short-circuit current density(J_(sc)),represent the great potential of solar radiation utilization,but suffer from the problem of increased interfacial charge recombination and reduced open-circuit voltage(V_(oc)).Herein,we report that an insertion of ultrathin Al_2O_3 layer(ca.1.2 A thickness)at the interface of ZnO nanowires(NWs)and Pb S quantum dots(QDs)could remarkably improve the performance of DBH-QDSCs fabricated from them,i.e.,an increase of V_(oc) from 449 mV to 572 mV,Jsc from21.90 mA/cm~2 to 23.98 mA/cm~2,and power conversion efficiency(PCE)from 4.29% to 6.11%.Such an improvement of device performance is ascribed to the significant reduction of the interfacial charge recombination rate,as evidenced by the light intensity dependence on Jsc and Voc,the prolonged electron lifetime,the lowered trap density,and the enlarged recombination activation energy.The present research therefore provides an effective interfacial engineering means to improving the overall performance of DBH-QDSCs,which might also be effective to other types of optoelectronic devices with large interface area.     

数学文化观念下的“0．618法”教学实践

在数学文化的观念下,笔者对上海市二期课改高三年级文科拓展教材第二单元“优选与统筹”中的一节选学内容“0．618法”进行了教学尝试．下面是这堂时间为60分钟的拓展课的教学片断实录。     

数学与文学——拓展教学的一次尝试

“数学与文学”是上海二期课改高三年级文科教材第五单元“数学与文化艺术”中的一节拓展内容．这个内容充分体现数学是人类文化的重要组成部分,在培养文科生的数学学习兴趣和建立正确的数学价值观等方面有着一定的教育价值．笔者在本校高三的一个文科班进行教学尝试,希望通过这样的拓展教学让文科生对数学产生新的感知,从而激发数学学习的兴趣,并逐步意识到数学素养是现代公民必备的基本素养,进而产生学习数学的动力．     

数学与文学——拓展教学的一次尝试

正"数学与文学"是上海二期课改高三年级文科教材第五单元"数学与文化艺术"中的一节拓展内容.这个内容充分体现数学是人类文化的重要组成部分,在培养文科生的数学学习兴趣