▁solar ▁cells ▁and ▁for ▁multi - j unction ▁solar ▁cells . ▁ ▁The ▁first ▁known ▁oper ational ▁use ▁of ▁Ga As ▁solar ▁cells ▁in ▁space ▁was ▁for ▁the ▁V ener a ▁ 3 ▁mission , ▁launched ▁in ▁ 1 9 6 5 . ▁The ▁Ga As ▁solar ▁cells , ▁manufact ured ▁by ▁K v ant , ▁were ▁chosen ▁because ▁of ▁their ▁higher ▁performance ▁in ▁high ▁temperature ▁environments . ▁ ▁Ga As ▁cells ▁were ▁then ▁used ▁for ▁the ▁L un ok hod ▁ro vers ▁for ▁the ▁same ▁reason . ▁ ▁In ▁ 1 9 7 0 , ▁the ▁Ga As ▁heter ost ruct ure ▁solar ▁cells ▁were ▁developed ▁by ▁the ▁team ▁led ▁by ▁Z hor es ▁Al fer ov ▁in ▁the ▁USS R , ▁ach ieving ▁much ▁higher ▁effic ien cies . ▁In ▁the ▁early ▁ 1 9 8 0 s , ▁the ▁efficiency ▁of ▁the ▁best ▁Ga As ▁solar ▁cells ▁sur pass ed ▁that ▁of ▁conventional , ▁cry st all ine ▁sil icon - based ▁solar ▁cells . ▁In ▁the ▁ 1 9 9 0 s , ▁Ga As ▁solar ▁cells ▁took ▁over ▁from ▁sil icon ▁as ▁the ▁cell ▁type ▁most ▁commonly ▁used ▁for ▁phot ov olta ic ▁arrays ▁for ▁satellite ▁applications . ▁Later , ▁dual - ▁and ▁triple - j unction ▁solar ▁cells ▁based ▁on ▁Ga As ▁with ▁g erman ium ▁and ▁ind ium ▁gal li um ▁ph osph ide ▁layers ▁were ▁developed ▁as ▁the ▁basis ▁of ▁a ▁triple - j unction ▁solar ▁cell , ▁which ▁held ▁a ▁record ▁efficiency ▁of ▁over