Page - 180 - in Photovoltaic Materials and Electronic Devices

5  circuit  current  (Is.c)  with  the  effect  of  our  synthesized  nanoparticle  coating  compared  to  both  quite  stable  open  circuit  voltage  (Vo.c)  and  fill  factor  (F.F).  Overall,  the  increase  in  the  current,  and  consequently  the  power,  could  be  explained  due  to  the  increase  in  the  rate  of  photoelectrons,  whether  through  a  higher  generation  rate  due  to  optical  conversions  and/or  the  better  mobility    due  to  a  conductive  nanostructure  coating.  (a)  (b) Figure  5.  (a)  P–V  curve  and  (b)  I–V  curve  of  silicon  solar  cells  in  both  the  uncoated  (normal)  case  and  those  coated  with  REDC  NPs.  Table  1.  Comparison  between  coated  and  un‐coated  cells.  Condition  ܄࢕ .ࢉ ۷࢙ .ࢉ F.F  િ  %  Uncoated  0.5155 0.1537 0.6301 15.1075 coated  cell  0.5095 0.1718 0.6322 16.7452 Beside  the  advantage  of  multi‐optical  conversions  of  REDC  NPs,  these  nanoparticles  have  the  ability  to  improve  the  electrical  conductivity  of  the  generated  photoelectrons  of  solar  cells  through  the  great  number  of  formed  O‐vacancies.  Then,  we  aimed  to  simulate  Si  solar  cells  before  and  after  the  REDC  NP  layer  coating  through  studying  the  normalized  generation  rate  and  field  distribution.  Figure  6  shows  the  difference  in  generation  rate  curves,  and  the  surface  electric  field  distributions  are  shown  in  Figure  7a,b.  A  simulation  model  has  been  built  in  a  two‐dimensional  (2D),  semiconductor  module.  This  model  deals  with  REDC  NPs  as  it  is  a  conductive  layer  with  a  band  gap  ܧ௚ ൌ 3.31 eV,  room  temperature  conductivity  σൌ77 ൈ10ି଺ S/cm ,  and  electron  mobility  μୣൌ2.8 ൈ 10ି଻ cmଶ/V൉ s  [20,21].  From  Figure  6,  it  has  been  proved  that  a  REDC  NP  coated  cell  has  a  little  bit  of  improvement  in  the  generation  rate  curve.  The  difference  between  the  maximum  of  the  curves  before  and  after  the  NP  coating  layer  is  calculated  to  be  about  0.408%.  That  gives  an  indication  that  the  conductivity  impact  of  the  coating  nanoparticles  has  a  major  impact  in  the  solar  cellʹs  efficiency  increase  rather  than  the  optical  conversions.  Figure5. (a)P–Vcurveand(b) I–Vcurveofsiliconsolarcells inboththeuncoated (normal) caseandthosecoatedwithREDCNPs. Beside the advantage of multi-optical conversions of REDC NPs, these nanoparticleshavetheabilitytoimprovetheelectricalconductivityofthegenerated photoelectrons of solar cells through the great number of formed O-vacancies. Then, we aimed to simulate Si solar cells before and after the REDC NP layer coating through studying the normalized generation rat and field distribution. Figure 6 shows the differen e in generation rate curves, and th surface electric field distributions are shown in Figure 7a,b. A simulation model has been built in a two-dimensional (2D), semiconductor module. This model deals with REDC NPs as it is a conductive layer with a b nd g p Eg “ 3.31 eV, room temperature conductivityσ“ 77 ˆ10´6 S{cm, and electron mobilityµe“ 2.8 ˆ 10´7 cm2{V¨s[20,21]. FromFigure6, ithasbeenprovedthataREDCNPcoatedcell has a little bit of improvement in the generation rate curve. The difference between themaximumof thecurvesbeforeandafter theNPcoating layer iscalculatedtobe about 0.408%. That gives indication that the conductivity impact of the coating nanoparticleshasamajorimpact inthesolarcell'sefficiencyincreaseratherthanthe optical conversions. 180