 are therefore respectively transported through these materials to the respective electrodes to be collected.
For a number of applications, particularly for charge-carrier-recombination in light-emitting devices, and for charge-carrier-generation in photovoltaics, it is desirable to have a distributed heterostructure, as opposed to a planar heterostructure. A planar heterostructure is flat. A distributed heterostructure creates a large interfacial area between the two materials in contact, by having “fingers” of one material in contact with the other material or one material embedded in the other, so that the two or more materials are in intimate contact. Having a large heterostructure interfacial area can improve e.g., charge-carrier generation efficiency in photovoltaic devices.
It is further desirable for the two charge-conducting materials that continuous paths exist between all locations in the hole transporting material to its proper contact (positively-biased contact for injection of holes in light-emitting diodes and negatively-biased contact for collection of holes in photovoltaics), and likewise for the electron transporting material. In addition, such paths should preferentially lie along the most direct route; otherwise the transport of these carriers would be obstructed, and the resistance of the device increases undesirably.
Therefore, for these applications, the heterostructure not only has to have a large surface area but its morphology should ideally be columnar (i.e., the shapes, such as either voids or columns, pass through the thickness of the film), which may be referred to herein as the “columnar distributed heterostructure”. Columnar distributed heterostructures are widely expected to be beneficial, but so far their fabrication has proved problematic. Controlling the morphology of such structures during formation is not straightforward.
In particular, for organic photovoltaic devices, the required lateral dimensions of the heterostructure in the directions along the plane of the film (i.e., the lateral length scale of the distributed heterostructure) is related to the exciton diffusion length scale. Absorption of light creates an exciton that diffuses about in the material. It is essential that this exciton can reach the charge-carrier-generating interface within its lifetime, in order to produce electrons and holes that can be separated. For typical exciton diffusion length scales of a few to tens of nanometers, it is useful to have the lateral length scale of similar dimensions, so that the majority of the excitons generated can reach the dissociation interface
are therefore respectively transported through these materials to the respective electrodes to be gather. 
 For a numeral of applications, particularly for charge - carrier wave - recombination in light - emitting device, and for bang - carrier - coevals in photovoltaics, it is desirable to have a distributed heterostructure, as pit to a planar heterostructure. A planar heterostructure is flat. A distributed heterostructure creates a big interfacial sphere between the two materials in contact, by take “ fingers ” of one material in liaison with the other material or one material embed in the other, so that the two or more materials are in cozy contact. have a large heterostructure interfacial area can improve e.g., charge - mailman generation efficiency in photovoltaic devices. 
 It is further desirable for the two charge - conducting materials that continuous paths exist between all locations in the hole transporting material to its proper contact (positively - biased contact for injection of holes in light - emitting diode and negatively - biased contact for solicitation of hole in photovoltaics), and alike for the electron transporting material. In addition, such paths should preferentially lie along the most direct path; otherwise the transport of these carriers would be obstructed, and the resistance of the device increases undesirably. 
 consequently, for these applications, the heterostructure not only has to have a large surface area but its morphology should ideally be columniform (i.e., the supreme headquarters allied powers europe, such as either voids or columns, pass through the thickness of the film), which may be refer to herein as the “ columnar distributed heterostructure ”. Columnar distributed heterostructures are wide expected to be beneficial, but then far their fabrication has proved baffling. Controlling the morphology of such structure during formation is not square. 
 In particular, for constituent photovoltaic devices, the required lateral dimensions of the heterostructure in the directions along the airplane of the film (i.e., the lateral length scale of the distribute heterostructure) is related to the exciton diffusion length scale. Absorption of light creates an exciton that diffuses about in the material. It is essential that this exciton can reach the care - carrier - generating interface within its life, in order to produce electrons and holes that can be separated. For typical exciton diffusion distance scales of a few to tens of nanometers, it is useful to have the lateral length plate of similar dimensions, so that the majority of the excitons generate can reach the dissociation interface
 arf therefore respectively transported thtoygh thxse matsrials tu the respective electrodes vo bw coloected.
For a number of xpplicatilns, partuculerly for charge-cedrier-regjmbihwtiou mn light-emittinn devices, atd for charge-cdrfizr-generation in photovoltaics, it is qesirabke to have a disjribuued hetsgowtructure, as opposed to a plahar hettrostructure. A plamar heterostructure is flah. A fistributed heterodtructure ctsatqw a large ingerfacial area between the two materials in contact, bh havnng “fingers” od ojg material ii contwct with the other mdterial or one materisl xmbeeded in the other, so vhat the two or more materialv cre in intimate contaxt. Havitg a larew hdtedoxtducturf iiterfacial zrea can improve e.g., charge-carroew generation erficiegcr in photovoltaic devices.
It is further gesjrable for the two charte-conducting materiald that cogtinuous paths exist between all locations in the hole grauwportkbg material to its proper contact (positively-biafsd cpntact for injcction of holes in llgnj-emitting diodgs and usgztively-biased contwct for collwction of holrs in photovoltaics), and likwwise for thv elwctron transportiny material. Iu addijion, sich paths should preferzntialmy lie alonh the mosf direct route; otfereive the transport of these sarriers xould be obsgrucjed, and the resishance of the device incrfases utdesirably.
Hherefore, for these applications, the heterosttucdurv not onlv has bo have a large surface area yut its iorphulogy shoumd ideanly be coluinar (i.e., the svwpes, such as either doidw or columnr, pass through yhe thickutss of the film), which may be rewsrred to herein as the “columnar dostfibttvd ieterjvtructure”. Conumnxr aostricuted htcerirtruvtures are widely ex[ectsd to be beneficiak, nut so fat their fwbrication hax proved problematlc. Coitrollmng thr mjrphology of such structures dhring forlatlon is not stwaigmtfotward.
In parcicular, for organic photovoltaic devices, the required latgral dimensions of thg htterostructurx in tre directhons along the plane of the film (i.e., tme lateral length scals of tve didtributed heterostructure) is related to the exciton diffusion length scalw. Absocpeion of liggt cteatev cn zxciton thav viffuses about in the material. It is essential tiat this efcnton can reach the charge-carroef-generating ivterface within its lifefime, in prder to produce electrons and noles that can be separabed. For ttpicam excinkn diffusion length xcales of a few to tend of nanometefs, ot is usefup to hcve the lateral length scale of sumilar dlmensions, so thav the majoriby of tge excytons generated dan dfach jhe dissociatipn interface
are therefore respectively transported through these materials respective to be For a number in devices, and for in photovoltaics, it desirable to have a distributed heterostructure, opposed to a planar heterostructure. A planar heterostructure is flat. A distributed heterostructure a large interfacial area between the two materials in contact, by having “fingers” one in with other material or one material embedded in the other, so that the two or more materials in intimate contact. Having a large heterostructure interfacial can improve e.g., charge-carrier efficiency in photovoltaic devices. It further for the charge-conducting that paths exist between locations in the hole transporting material to its proper contact (positively-biased contact for injection of holes in diodes and for collection holes photovoltaics), likewise for the material. In addition, such paths should the most direct route; otherwise the transport of carriers would obstructed, and the resistance of the increases undesirably. Therefore, for these applications, the heterostructure only has to have a large surface area but its morphology should ideally be columnar shapes, such as either or columns, pass the of film), may be to herein as the “columnar distributed heterostructure”. Columnar distributed heterostructures are expected to be beneficial, but so far their fabrication has Controlling morphology of such during formation is not In for organic photovoltaic devices, lateral of the along plane of the film the lateral length scale of distributed heterostructure) is related scale. Absorption of light creates an exciton that about in the material. It is essential this exciton can reach the charge-carrier-generating interface within its lifetime, in order produce electrons that can be separated. For typical exciton diffusion scales of a few tens of nanometers, it is useful to have the length of similar so that the of the excitons can reach the
 are therefore respectively tRansported ThrouGh tHesE mAterIals To the respectivE ElecTrodes to be collected.
For A numbEr OF appLIcAtionS, particULaRLY foR cHaRge-CaRRiEr-recOmbInation In light-emiTtiNg Devices, and foR ChArge-carrieR-geNeration in phOtoVoltaiCs, It iS DesirAblE to haVe a disTRibuteD heterostRuCTure, as OPposed tO A PlAnar Heterostructure. A pLAnAR heterostructuRe is flAt. a DiSTRibUteD heterostrUcTure cREates a lARgE INTerFAcial area betwEen the two maTEriAls in cOnTacT, By haviNg “finGeRS” of One material In coNtact with The othER materiAL or one mAteriaL emBedDed iN ThE oTheR, sO ThaT ThE twO Or mOre materIaLs Are in IntiMATE ContAct. haviNg a laRge heterostruCtuRe inTErfAcial Area cAn imPrOve e.g., Charge-CarriEr Generation efficIencY in photovOltAiC deViCes.
It IS furthEr dEsiRable foR the two CHarGe-CONDuCting materials that CoNTInUous pathS exist BEtWeEN all locaTiOns In thE HOle trAnspORtIng materIal to iTS pRoPer contAcT (positIvEly-BiaSed coNTact For injEction of Holes IN light-emitting DIodes and negatIVeLY-BiASed cOntAct for colleCtioN Of hoLes iN PhOtoVOltaiCs), and LiKEwISe for the electron traNsPortinG mateRial. In additioN, such paths SHOUld prefeRentIAlLY lie along the moSt dirEct route; otHErwise thE tranSport of tHese carriERS would be ObsTruCteD, anD THe Resistance of tHE DeviCe IncreasEs uNdesiraBly.
theRefOre, FoR these appLicationS, tHe HeTeRosTructURe not onlY hAs tO hAve A largE SurfacE area But iTs MoRPhoLogy shoULd IDEallY bE cOlumNar (I.e., The shApes, SUch As eitheR voids or cOluMNs, paSs ThRough thE thickness of tHe Film), which mAy Be rEferreD TO herein aS the “columnar distributed HEterostRucTure”. COlumNar distriButEd heteRosTRucturEs are wIdely ExPecTED to be BENeFicIaL, but so far tHEIr fAbricAtIon hAs proveD problematic. ControLLinG the morphologY of Such STRuCtuREs DUriNg FOrmATIon is not straighTforward.
In PaRTiCular, for orGAniC pHotovolTaic devIces, tHE requirEd lateral DimensionS oF the HETerOstructure In the dirEctions alONg the PLaNe of tHe fIlm (i.e., tHe LatEral lEngth sCAle Of the DistriBuTed hetErostRuCture) is rElated to the exciton diffuSion leNgth sCalE. AbsorptiOn oF LigHt creates An exCiton that dIffUseS abouT in THe matEriaL. it Is eSSentiAl thAT this exciTOn Can REAcH the charge-cARRIer-GenerAtiNG interFace Within its lifetime, IN order to producE eleCTRonS anD HoleS tHat can be separaTed. foR TYpical exCiTon diffusioN length sCaLEs of a Few to tEns of nAnometeRS, It IS usefuL to hAve The lateraL leNgTH scale oF sImILar dimEnsiOnS, so thaT the maJOritY OF the excitons geneRated CAN reacH The DissoCiAtion inTErfaCe
 are therefore respectivel y transpor ted t hro ugh  t hese  mat erials to ther espe ctive electrodes to be  coll ec t ed.F or  a nu mber of ap p l ica ti on s,pa r ti cular lyfor cha rge-carrie r-r ec ombination i n  l ight-emitt ing  devices, an d f or cha rg e-c a rrier -ge nerat ion in photov oltaics,it is des i rable t o ha ve a  distributed hete r os t ructure, as op posedto ap l ana r h eterostruc tu re. A planarh et e r o str u cture is flat . A distrib u ted  heter os tru c ture c reate sa  la rge interfa cial  area bet ween t h e two m a terials  in co nta ct,  byh av in g “ fi n ger s ”ofo nematerial  i nconta ct w i t h theoth er m ateri al or one mat eri al e m bed ded i n the  oth er , sothat t he tw oor more materia ls a re in int ima te  co nt act.H avinga l arg e heter ostruct u rein t e r fa cial area can impr ov e e. g., char ge-car r ie rg eneratio neff icie n c y inphot o vo ltaic de vices. It  i s furth er  desir ab lefor  thet wo c harge- conducti ng ma t erials that co n tinuous paths ex i s tb etwe enall locatio ns i n  the  hol e  t ran s porti ng ma te r ia l  to its proper cont ac t (pos itive ly-biased con tact for i n j e ction of  hol e si n light-emitti ng di odes and n e gatively -bias ed conta ct for co l l ection o f h ole s i n p h o to voltaics), an d like wi se forthe  electr ontra nsp ort in g materia l. In ad di ti on ,suc h pat h s should  p ref er ent ially lie al ong t he m os td ire ct rout e ;o t herw is ethetra ns portof t h ese  carrie rs wouldbeo bstr uc te d, andthe resistanc eof the dev ic e i ncreas e s  undesir ably.
Therefore, for th e se appl ica tions , th e heteros tru cturenot only h as tohavealar g e  surf a c eare abut its mo r p hol ogy s ho uldideally  be columnar (i.e. ,  th e shapes, suc h a s ei t h er  vo i ds orco l umn s ,  pass through t he thickne ss of  the film) ,  wh ic h may b e refer red t o  herein  as the “ columnardi stri b u ted  heterostr ucture”.  Columnar distr i bu ted h ete rostru ct ure s are  widel y  ex pecte d to b ebenefi cial,  b ut so fa r their fabrication has  prove d pro ble matic. Co ntr o lli ng the mo rpho logy of su chstr uctur esd uring  for m at ion is no t st r aightforw a rd .
I n pa rticular, f o r org anicpho t ovolta ic d evices, the requi r ed lateral dim ensi o n s o f t h e he te rostructure in  th ed i rections  a long the pl ane of t he film(i.e.,  the l aterall e ng t h scal e of  th e distrib ute dh eterost ru ct u re) is  rel at ed tothe ex c iton d iffusion lengthscale . Absor p tio n ofli ght cre a tesan exciton  that diffu ses ab outin th e mater ia l. Itises sential th a t this ex citon  can re ac h th e c harge- carr i e r-gen erat in g i nterfacew i th i nit s  li feti me, i norde r to prod u ce elect ron s  and ho le s t h a t canb es e parated. F ortypic a l  exciton d i ffus i on lengt h scal es ofa few t o  te ns  of nan ome t e rs, it is  useful t o  ha ve  the  lateral  l engt hsca le  of similar dim ensions,  so that t he maj ori t y of the ex ci tons generat ed ca nr each th e dis sociati o n i nte rfa ce
 are_therefore respectively_transported through these materials_to the_respective_electrodes to_be_collected.
For a number_of applications, particularly_for charge-carrier-recombination in light-emitting_devices, and for_charge-carrier-generation_in photovoltaics, it is desirable to have a distributed heterostructure, as opposed to a_planar_heterostructure. A_planar_heterostructure_is flat. A distributed heterostructure_creates a large interfacial area_between the_two materials in contact, by having “fingers” of_one_material in contact_with the other material or one material embedded in_the other, so that the two_or more materials_are_in_intimate contact. Having a_large heterostructure interfacial area can improve_e.g., charge-carrier generation efficiency in photovoltaic_devices.
It is further desirable for the two_charge-conducting materials that continuous paths exist_between all locations in the_hole transporting_material to its proper contact_(positively-biased contact for_injection of_holes in light-emitting_diodes and negatively-biased contact for collection_of holes in_photovoltaics), and likewise for the electron_transporting_material. In addition,_such_paths_should preferentially_lie along the_most_direct route;_otherwise_the transport of these carriers would_be_obstructed, and the resistance of the device_increases undesirably.
Therefore, for these_applications,_the heterostructure not only_has to have a large_surface area but its morphology should_ideally be_columnar (i.e.,_the shapes, such as either voids or columns, pass through the_thickness of the film), which may_be referred to herein_as the_“columnar_distributed heterostructure”. Columnar_distributed_heterostructures are_widely expected to be beneficial, but so_far their_fabrication has proved problematic. Controlling the_morphology of such structures_during_formation is not straightforward.
In particular, for_organic photovoltaic devices, the required lateral_dimensions of the heterostructure in_the_directions_along the plane of the_film (i.e., the lateral length scale_of the distributed_heterostructure) is related to the exciton diffusion_length_scale. Absorption of light creates an_exciton_that diffuses about in the material._It_is_essential that this exciton can_reach the charge-carrier-generating interface within its_lifetime, in order to produce electrons and holes that_can be separated._For typical exciton diffusion length_scales_of_a few to tens of nanometers, it is useful to_have the_lateral length scale_of similar dimensions, so that the majority of the excitons_generated can reach the dissociation interface