PerovskiteSolarCellsfortheGenerationofFuelsfromSunlightWangW.P.2016-10-20LogoGeneralIntroductionOutline1Photovoltaic-DrivenWaterSplitting2CO2Reduction3DiscussionandPerspective41.GeneralIntroduction1.1EnergyDemand,GlobalWarming,andtheNeedforStorage•Energysupply•Airpollution•ClimatechangeunbalanceddistributionWorldtotalenergyconsumption:15TW(2015)--30TW(2050)Cleanandrenewableenergysources:SolarenergyStorage?Lithiumionbatteriesandsupercapacitors:ExpensiveChemicalsfuels:Carbohydrate•Series/DC–DCpowerconverter•CO2reduction:fiveconventionalcells1.2AdvantagesofPerovskiteasLightHarvestersforSolarFuelGenerationOnlydevicesgeneratingsufficientVocfordrivingthecompletereactioncanachievenonzeroefficiencies.Advantagesofperovskitelightharvesters:IntrinsichighVocandbandgaptunability2PerovskitePhotovoltaic(PV)2.1OneCell-DrivenWaterSplitting•Onlylargebandgapoxidesshowefficiencieswithonecell•EffcienciesareverylowHypotheticalsingle-PVphotoelectrolysisdeviceAstheopen-circuitvoltageofasingleperovskitesolarcellcanbelargerthan1.23V,itisconceivablethat,forasystemusingefficientelectrocatalyststominimizetheoverpotential,onecellcoulddriveoverallwatersplittingCH3NH3PbI3(1.5eV),CH3NH3PbBr3(2.3eV)2.1OneCell-DrivenWaterSplittingVoc=1.5VPCE=10.4%Onecellwithhighopen-circuitvoltage2.1OneCell-DrivenWaterSplittingBasedonefficientEarth-abundantelectrocatalystsreportedintheliterature,whichcanreach20mAcm−2currentdensityatavoltagelowerthan1.5VforoverallwatersplittingSolartohydrogenconversionefficiency10%?OR2.2TwoinSeriesConnectedPerovskiteCellONECELL•Extremelylowoverpotential•FuctuationinrealsunlightTWOCELLsThisisthefirsttimethatefficiencyover10%hasbeenachievedwithlow-costlightharvestersandEarth-abundantelectrocatalysts.•STH:12.3%•TheoreticalSTH:17.8%(1.5eV)2.3TwoAbsorberTandemsTWOCELLS•Doubleilluminatedarea•Bandgap:Trade-offbetweentheCurrentandVoltageTwoAbsorberTandemsDespitegreatefforttowarddevelopingsuchtandems,thebestefficiencieshavereachedonlyaround1%STH:0.91%2.3TwoAbsorberTandemsCombiningthephotoanodeandphotovoltaicwithaplatinumcathodeforhydrogenevolution,standaloneone-sunwatersplittingphotocurrentsofnearly2mAcm−2wereachieved,correspondingtoaSTHefficiencyofnearly2.4%Photoanode:Fe2O3•mostwidelystudied•suitablebandgap•stability•naturalabundance2.3TwoAbsorberTandemsEfficienciesreach4.3%andupto3.0%inawireless“artificialleaf”configurationPhotoanode:BiVO4•highquantumefficiency•largeVoc2.4IdealTwoAbsorberSystemTheidealdual-absorbersystemcanberealizedbypairing1.6–1.8eVand1.0eVbandgapabsorbersinastackedtopandbottomconfiguration•top:1.0V•bottom:0.6V•Perovskitecellsshouldbemoresuitableastopabsorberspairedabovesmallerbandgapabsorbers•DevelopingsemitransparentperovskitesolarcellsUsetransparentconductivemetaloxides,Agnanowiresorcarbonnanotube(CNT)networkstomakesemitransparentperovskitesolarcells2.4IdealTwoAbsorberSystemIdealDual-AbsorberTandemWaterSplittingUsingPerovskitePhotovoltaicsandCuInxGa1−xSe2PhotocathodesBottomlightharvester:SiandCIGSPhotocurrentdensitySTHconversionefficienciesCH3NH3PbI32.1mAcm−22.6%CH3NH3PbBr35.1mAcm−26.3%AttemptsofusingmixedabsorberCH3NH3PbIxBr3−xwith1.7eVidealbandgapandhighefficiencywereunsuccessful.STH:27%3CO2ReductionH2•Highenergy•Clean•Store?•Transport?CO2Convertingsolarenergyintoliquidfuelorotherusefulcommodities•Closingtheanthropogeniccarboncycle•AbundantcarbonsourceHydrocarbonFormalelectrochemicalpotentialsforseveralCO2reductionpathwaysChem.Rev.115,12888–12935(2015)3.1PerovskitePV-DrivenCOGenerationfromCO2COistheproductthatstoresthelargestamountofenergypermoleculeChem.Rev.115,12888–12935(2015)•AuisoneofthebestcatalyststomakeCOfromelectrochemicalCO2reductionwithhighFaradicefficiencyatlowoverpotential.•Oxygenevolutionanodeusesiridiumoxide(IrO2):highactivity,stabilityagainstdissolution.MaximizetheFaradicefficiencyAdjustedtheareaoftheAuelectrode6.5%solar-to-COconversionefficiency4.1SystemDesignandEngineeringPutPVsintheelectrolytePutPVsoutsidewiredtocatalystelectrodesWhichisrationalorbetter?•Burieddevicelooksmoreelegant•Thiselegancemakesthedevicesufferfromthecorrosionofthelightharvestersintheelectrolyte•Blockageofthelightabsorptionbyputtingprotectionlayerandcatalystonthesurface4.2StabilityIssueandSolutionThestabilityofthesolarfueldevicesdescribedherearelimitedbythestabilityoftheperovskitesolarcellsHTM-free:long-termlightsoaking&heatstressat85°CStructureengineering:addingadditivesUsinginorganicCs-basedperovskiteasadditiveδ-FAPbI3δ-CsPbI3α-,β-FAPbI3cubic-CsPbI34.3PerspectiveDespiteremarkableefficiencieswereachieved,thereisstillalongwaytogotowardrealapplication.MembraneisnecessarytoseparatetheproductsASolarfluctuationmaychangethepotentialatthecatalystelectrode,whichmaychangetheselectivityoftheproductsBAnintegrateddevice:provideelectricitysupplyinthedaytimeandstoretheexcessenergyaschemicalfuelstokeepacontinuousenergysupplyCThankyou