Theefficiencyofthepoly（3-hexylthiophene）（P3HT）and[6,6]-phenylC61-butyricacidmethylester(PC61BM)basedorganicsolarcellswasenhancedbyusing1,2,4-trichlorobenzene（TCB）asaprocessingadditivetocontroltheblendmorphology.TheadditionofTCBimprovedthearrangementofP3HTwhichresultedingoodphaseseparatedblendfilms.Correspondingly,theoptimizedsolarcellsshowedapowerconversionefficiency（PCE）of4.17%withafillfactor（FF）of0.69,whichwerehigherthanthoseofcommonthermalannealingdevices（PCE3.84%,FF0.67）.Theefficiencywasfurtherimprovedto4.74%bythermalannealingat150°Cfor10minwithahigherFFof0.74.
