Seite - 10 - in Photovoltaic Materials and Electronic Devices

improved  compared  with  that  of  the  hole‐only  devices  without  any  additive.  The  result  indicates  that  even  though  the  thickness  of  the  film  with  PS  is  greater  than  that  without  PS  in  the  same  fabricate  condition,  the  hole  mobility  of  the  device  with  PS  is  better  than  that  without  PS,  which  shows  PS  can  be  good  for  hole  carrier  transport.  Moreover  it  further  demonstrates  that  the  improved  hole  carrier  transport  could  be  one  of  the  reason  for  the  increased  Jsc  of  OPVs  [30,31].    Figure  4.  J‐V  characteristic  curves  of  hole‐only  devices  with/without  3  v%  DIO  and/or  1  v%  PS.  4.  Conclusions  A  series  of  OPVs  with  PTB7:PC71BM  as  the  active  layer  are  fabricated  to  investigate  the  additive’s  effects  on  the  performance  of  the  OPVs.  DIO  and  PS  are  used  as  the  additives.  The  experimental  results  of  photovoltaic  performance  reveal  an  enhancement  of  Jsc  from  10.47  to  16.37  mA/cm2  and  FF  from  49.65%  to  71.68%  by  adding  DIO  and  PS.  As  a  result,  the  PCEs  of  the  OPVs  are  improved  from  4.11%  to  8.92%,  with  117%  improvement  compared  with  the  OPVs  based  on  PTB7:PC71BM  without  additives.  The  positive  effect  of  DIO  and  PS  additives  on  the  performance  of  the  OPVs  should  be  attributed  to  the  increased  absorption  and  charge  carrier  transport  and  collection.  Acknowledgments:  This  work  was  supported  by  the  Fundamental  Research  Funds  for  the  National  Natural  Science  Foundation  of  China  (No.  61575019,  51272022  and  11474018),  the  National  High  Technology  Research  and  Development  Program  of  China  (863  Program)  (No.  2013AA032205),  the  Research  Fund  for  the  Doctoral  Program  of  Higher  Education  (No.20120009130005  and  20130009130001),  and  the  Fundamental  Research  Funds  for  the  Central  Universities  (No.  2012JBZ001).  Author  Contributions:  The  process  design,  experimental  work  and  writing  of  the  first  draft  of  the  manuscript  were  all  carried  out  by  Lin  Wang.  Suling  Zhao  and  Zheng  Xu  supervised  every  step  of  the  entire  work.    Jiao  Zhao,  Di  Huang  and  Ling  Zhao  collaborated  with  the  AFM  analysis.  Conflicts  of  Interest:  The  authors  declare  no  conflict  of  interest.  0.01 0.1 1 1E-5 1E-4 1E-3 0.01 0.1 Voltage / V Device 1 Device 2 Device 3 Device 4 Figure 4. J-V characteristic curves of hole-only devices with/without 3 v% DIO a d/or1v%PS. 4. Conclusions A series of OPVs with PTB7:PC71BM as the active layer are fabricated to investigate the additive’s effects on the perfor ance of the OPVs. DIO and PS are used as the additives. The experimental results of photovoltaic performance reveal an enhancement of Jsc from 10.47 to 16.37 mA/cm2 and FF from 49.65% to 71.68% by adding DIO and PS. As a result, the PCEs of the OPVs are improved from 4.11% to 8.92%, wit 117% improvement compared with t e OPVs based on PTB7:PC71BM without additives. The positive effect of DIO and PS additives on theperformanceof theOPVsshouldbeattributedto the increasedabsorptionand chargecarrier transportandcollection. Acknowledgments: This work was supported by the Fundamental Research Funds for the National Natural Science Foundation of China (No. 61575019, 51272022 and 11474018), the National High Technology Research and Development Program of China (863 Program) (No. 2013AA032205), the Research Fund for the Doctoral Program of Higher Education (No.20120009130005 and 20130009130001), and the Fundamental Research Funds for the CentralUniversities (No. 2012JBZ001). AuthorContributions: Theprocessdesign,experimentalworkandwritingof thefirstdraft of themanuscriptwereall carriedoutbyLinWang. SulingZhaoandZhengXusupervised every step of the entire work. Jiao Zhao, Di Huang and Ling Zhao collaborated with the AFManalysis. Conflictsof Interest: Theauthorsdeclarenoconflictof interest. 10