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1、AcceptedManuscriptThisarticlecanbecitedbeforepagenumbershavebeenissued,todothispleaseuse:Q.Wei,W.Tong,B.Wei,M.ZhangandX.Peng,Phys.Chem.Chem.Phys.,2019,DOI:10.1039/C9CP03128F.ThisisanAcceptedManuscript,whichhasbeenthroughtheRoyalSocietyofChemistrypeerreviewprocessandhasbeenacceptedforpublication.Acce
2、ptedManuscriptsarepublishedonlineshortlyafteracceptance,beforetechnicalediting,formattingandproofreading.Usingthisfreeservice,authorscanmaketheirresultsavailabletothecommunity,incitableform,beforewepublishtheeditedarticle.WewillreplacethisAcceptedManuscriptwiththeeditedandformattedAdvanceArticleasso
3、onasitisavailable.YoucanfindmoreinformationaboutAcceptedManuscriptsintheInformationforAuthors.Pleasenotethattechnicaleditingmayintroduceminorchangestothetextand/orgraphics,whichmayaltercontent.ThejournalsstandardTerms&ConditionsandtheEthicalguidelinesstillapply.InnoeventshalltheRoyalSocietyofChemist
4、rybeheldresponsibleforanyerrorsoromissionsinthisAcceptedManuscriptoranyconsequencesarisingfromtheuseofanyinformationitcontains.PCCPPhysicalChemistryChemicalPhysicsARTICLEJournalName一吊d9T!RA6-0知0以8uo罢工UJO送oouq占pg8UUOSJoqs.wuDqpopeocmoa.6sSEn9-u。-3qs=qndFig4.Electronicbandstructuresforthenewsiliconpha
5、sesusingfunctionalHSE06.Phases氏心(GPa)琮in(GPa)Enuix.fEminlm-3m80.844.91.80C2/c146.755.42.6514/nicm183.671.22.58IMmmm75.427.52.74P2lm185.5114.61.62P4/mbm14L647.92.96Diamondsilicon182.6106.81.71Table4ThecalculatedmaximumandminimumvaluesofYoungsmodulus(Ena.、，Emin),andthe吼/%_ratioofthenewstructuresanddia
6、mondsilicon.Tofurtherexplorethelightabsorptionperformanceofthesenewstructures,wecalculatedtheimaginarypartoftheirdielectricfunctionsattheHSE06level.Forcomparison,diamondsiliconwasalsocalculated.TheresultsareshowninFig.5.Thesolarspectrumcanbedividedintothreeregions,infrared,visible,andultraviolet,acc
7、ordingtotheirphotonenergies.Sincethesolarradiationisconcentratedinthevisibleregion(about1.63.2eV),favourablephotovoltaicmaterialsneedtohavegoodabsorptionofvisiblelightaswellasinfrared.Asmentionedpreviously,thedirectbandgap3.4eV5ofdiamondsiliconistoolargeandabsorbmostlyultravioletphotonswhichrepresen
8、tsonlyasmallportionofthesolarspectrum.However,thesixnewsiliconallotropespredictedinthisworkhaveviewArticleom.nemuchstrongerabsorptionin(hevisibleregiondue(olheirdirectbanddoi：10.1039/C9CP03128Fgapintherangeof0.6581.470eV.FromFig.5.onecanseethatamongthesixnewphasesanddiamondSi,theC2/cphasewithdirectb
9、andgapof1.470eVshowsbestlightabsorptionperformanceinthevisiblephotonenergyrangeof1.6-1.9eVand2.73.2eV.whiletheI4!rmnmphasewiththedirectgapof0.671eVexhibitshighestopticalabsorptionintherangeof1.92.7eV.Itwasdemonstratedthatthemaximumphotoelectricconversionefficiency33.7%canbeachievedwhenthebandgapis1.
10、34eVforasingle-gapphotovoltaicdevice32.Atandemsolarcellsystemwasproposedbystackingseveralhomojunctioncellstogethertoformarrays,anditwasfoundthatathree-orfour-stackedcellcanboosttheefficiencyuptomorethan60%.whichrequiresa0.50.6eVbandgapabsorbertocapturethelow-energyphotons31.ThesixnewSiphaseshavethed
11、irectbandgapintherangeof0.658to1.470eVandarepromisingmaterialinphotovoltaicapplication.ConclusionsSixnewsiliconallotropeswithdirectbandgapswerepredictedbyperformingSisubstitutionofcarboninknowncarboncrystalstructuresandhigh-throughputcalculations.Thesesixstructuresarein仞-3】，C2/c,14/mnun,P2/ni,andP4/
12、nihmspacegroup,respectively.Allofthenewphaseswereproventobethermodynamicallystableviathephononspectrumcalculationsandmechanicallystablebyevaluatingtheirelasticconstantsatambienlpressure.Moreimportanlly,lhenewphasesallhavedirectbandgapsinlherangeof0.6581.470eVwhichissuperiorforphotovoltaicapplication
13、.Moreover,thenewsiliconallotropesdemonstratesignificantlyimprovedphotonabsorptioncomparedlodiamondsiliconbyinvestigatingtheimaginarypartsoftheirdielectricfunctions,whichsuggestlhal(henewphasesarepromisingpholovollaicmaterialsinihin-filmandlandcmsolarcellapplications.InfraredregionP4inibmUltravioletr
14、egionDiamondsiliconPhotonenergy(eV)Fig.5ImaginarypartofdielectricfunctionIbrlhesixnewsiliconallotropesanddiamondSicalculatedattheHSE06level.U:奶a9.怜、,八/辱10 |J.Name.,2012,00,1-3ThisjournalisTheRoyalSocietyofChemistry20xxJournalNameARTICLE一2d6一ocfoeQCccrtezuJ。ABOculpfPUC3oopAqPQPBO一UMOci6-ocIsnefinv9一u
15、cpQqs二q3dConflictsofinterestTherearenoconflictstodeciare.AcknowledgementsThisworkwasfinanciallysupportedbytheNaturalScienceFoundationofChina(GrantNo.:11204007),theNaturalScienceNewStarofScienceandTechnologiesResearchPlaninShaanxiProvinceofChina(GrantNo.2O17KJXX-53).andNaturalScienceBasicResearchplaninShaanxiProvinceofChina(GrantNo.2019JM-353).WealsoacknowledgethecomputingfacilitiesatHighPerformanceComputingCenterofXidianUniversity.ReferencesX.-P.HaoandH.-L.Cui,J.KoreanPhys.Soc.、2014,65,4551.1 M.Amsler,S.Botli,M.A.L.Marques,T.J.LenoskyandS.Geodecker,Phys.Rev.B,2015,92,014101.2 Q.Fan
