题目内容：
Questionsarebasedonthefollowingpassage．
Thermoelectricmaterialscanconvertwasteheatdirectlyintoelectricity.TommiTynell,whoisadoctoralcandidateattheAaltoUniversitySchoolofChemicalTechnology,hasdevelopedhybrid(混合的)thermoelectricmaterialswhichcombineusefulpropertiesfromdifferenttypesofmaterials.
Hefoundthatbyaddingorganiclayersbetweenlayersofzincitispossibletoimprovetheperformanceofthermoelectricmaterials.Theorganiclayersarealsobelievedtohaveamajoreffectinreducingthermalconductivity,whichwouldbeveryusefulinthermoelectricmaterials.
Developingmoreefficientthermoelectricmaterialsisamajorchallenge,becausethephysicalpropertiesthataffecttheperformanceofthematerialsarenotindependentofeachother.Theoptimizationofamaterialisverydifficult,becauseasyouimproveonefeature,otherpropertiesmaydeteriorateatthesametime.
Thebiggestobstacletothebroadutilizationofthermoelectricgeneratorsisthelowefficiencyofcurrentlyknownthermoelectricmaterials.Inaddition,thebestexistingcompoundsdonotwithstandthehightemperaturesrequiredandoftencontainrareandharmfulelements.
Inhisresearch,Tynelladdedlayeruponlayerofnanoscalestructures,examiningtheirformationusingX-rayandinfrared(红外线的)devices.Intheresearch,thinfilmsofzincoxidewereused,becausezincoxideisoneofthemostpromisingthermoelectricoxidematerials.Oxidematerialsareenvironmentallyfriendlyandtheiravailabilityisnotaproblem.Itisbelievedthattheywillplayanimportantroleinthefuturedevelopmentofsustainableenergytechnologies.
Tynellcombinedatomiclayerdepositionandmolecularlayerdepositionandthussucceededinmanufacturingahybridsuperlattice(超晶格)composedoforganicandinorganiccompounds.Atomiclayerdepositionisanextremelyaccuratelycontrollednanofabricationprocess.Theprocesswasusedtoproducelayerednanostructures,withextremelythinorganiclayersalternatingwiththickerinorganiclayers.Threedifferentsourcematerialswereusedfortheorganicsubstance:hydroquinone,4-aminophenoland4,4'-oxydianiline.Alloftheorganicmoleculestestedwerefoundtoinfluencethethermoelectricpropertiesofthethinzincoxidefilm.
Althoughthestructuresofthestartingmaterialswerequitesimilar,thesizeoftheeffectwasquitevariabledependingonthesourcematerial.Hydroquinone(对苯二酚)wasthemostapplicableofthethree,becauseitformedthedesiredstructuresmosteasily.
TommiTynelldidhisdoctoralthesisinAcademyProfessorMaaritKarppinen'sresearchgroup.Theresearchofthegroupisuniqueinthatitisraretousehybridmaterialsinthermoelectricresearch.Onlyafewresearchgroupsintheworldarecurrentlyfocusedoninvestigatingthepropertiesofhybridmaterials.Byutilizingthermoelectricenergyharvestingitwillbepossibletoreduceourdependenceontraditionalenergysources.
Whateffectsdoorganiclayershaveonthermoelectricmaterials? A．Convertingheatintoenergythatisprovidedtohousehold.
B．Improvingtheirperformanceandcuttingoffthermalconductivity.
C．Transformingthermoelectricmaterialsintoelectricity.
D．Reducingthermoelectricmaterials'relianceondeposition.
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