Page - 171 - in Photovoltaic Materials and Electronic Devices

6 efficiency  will  dramatically  decrease  [27].  Despite  the  lower  efficiencies  in  our  ZnO‐based  DSSCs,  the  use  of  ZnO  nanorods  still  shows  high  potential  because  of  its  better  crystallinity  and  higher  electron  mobility.  To  overcome  the  chemical  instability  of  ZnO,  the  introduction  of  non‐ruthenium‐based  sensitizers  and  the  utilization  of  different  nanotechnological  architectures  of  ZnO  might  be  practical  approaches.  Figure  5.  (a)  J‐V  measurements  under  AM  1.5  illumination  (100  mA∙cm−2  )  and  (b)  IPCE  spectra  of  DSSCs  containing  ZnO  nanorods  grown  at  various  durations.  Shown  in  the  inset  of  Figure  5a  is  the  photovoltaic  performance  of  DSSC  employing  TiO2  nanoparticles.  4.  Conclusions  In  this  study,  we  prepared  ZnO  NRs,  with  a  two‐step  process  which  is  simple  and  easy,  for  use  as  photoanodes  in  DSSCs.  Moreover,  the  results  reveal  that  DSSCs  containing  longer  ZnO  NRs  demonstrate  higher  photovoltaic  performance  than  DSSCs  containing  shorter  ZnO  NRs.  Compared  with  shorter  ZnO  NRs,  longer  ZnO  NRs  exhibit  a  larger  surface  area,  which  enables  efficient  dye  Figure 5. (a) J-V measurements under AM 1.5 illumination (100 mA¨cm´2) and (b) IPCE spectra of DSSCs contai i g ZnO nanorods grown at various durations. Shown in the inset of Figure 5a is the photovoltaic performance of DSSCemployingTiO2 nanoparticles. 4. Conclusions In this study, we prepared ZnO NRs, with a two-step process which is simple andeasy, foruseasphotoanodes inDSSCs. Moreover, theresults reveal thatDSSCs containing longer ZnO NRs demonstrate higher photovoltaic performance than DSSCs containing shorter ZnO NRs. Compared with shorter ZnO NRs, longer ZnO NRs exhibit a larger surface area, which enables efficient dye loading and lightharvesting,reducedchargerecombination,andfasterelectrontransport. These improvementsenhancedpowerconversionforapplication inDSSCs. Acknowledgments: Acknowledgments: The authors would like to thank the experimental support from Hsiu-Po Kuo in Chang Gung University. This work was supported by the Green Technology Research Center of Chang Gung University and the Ministry of Science and Technology of Taiwan under contract numbers MOST104-2622-E-182-003-CC3 andMOST104-2112-M-182-005. Author Contributions: Author Contributions: Fang-I Lai and Jui-Fu Yang designed and carried out the experiment and statistical analysis and participated in drafting the manuscript. Shou-Yi Kuo supervised the research and revised the manuscript. All authors readandapprovedthefinalmanuscript. Conflictsof Interest: Conflictsof Interest: Theauthorsdeclarenoconflictof interest. References 1. O’Regan, B.; Grätzel, M. A low-cost, high-efficiency solar cell based on dye-sensitized colloidalTiO2 films.Nature1991,353, 737–740. 171