All-polymer　solar　cells　(all-PSCs)　can　offer　unique　merits　of　high　morphological　stability　to　thermal　and　mechanical　stress.　To　realize　their　full　potential　as　flexible　or　wearable　devices,　it　is　highly　desirable　that　the　all-PSCs　can　be　fabricated　from　a　green　solvent　with　simple　post-treatment　to　avoid　thermal　annealing　on　the　flexible　substrate.　This　posed　a　severe　challenge　on　material　design　to　tune　their　properties　with　suitable　solubility,　aggregation,　and　morphology.　To　address　this　challenge,　here,　a　simple　bicomponent　random　approach　on　a　D-A-type　polymer　donor　was　developed　by　just　varying　the　D-A　molar　ratio.　Under　this　approach,　a　series　of　new　random　polymers　PBDTa-TPDb　with　different　molar　ratios　of　the　D　component　of　2D-benzo[1,2-b:4,5-b＇]dithiophene　(BDT)　and　A　component　of　thieno[3,4-c]pyrrole-4,6-dione　(TPD)　were　designed　and　synthesized.　The　energy　levels,　light　absorption,　solubility,　and　packing　structure　of　random　donors　PBDTa-TPDb　were　found　to　vary　substantially　with　the　various　D-A　molar　ratios.　The　devices　based　on　PBDTa-TPDb/P(NDI2HD-T)　were　fabricated　to　explore　the　synergistic　effects　of　the　processing　solvent　and　composition　of　D-A-type　random　polymers.　The　results　show　that　nanoscale　morphology,　balanced　miscibility/crystallinity　of　blend,　and　photovoltaic　properties　could　be　rationally　optimized　by　tuning　the　composition　of　random　donors.　As　a　result,　as-cast　all-PSC-based　optimal　donor　PBDT5-TPD4　achieves　the　best　power　conversion　efficiency　(PCE)　of　8.20%　processed　from　a　green　solvent,　which　performs　better　than　that　the　reference　polymer　(PCE:　6.41%).　This　efficiency　is　the　highest　value　for　all-PSCs　from　BDT-TPD-based　donors.　Moreover,　the　optimized　devices　were　relatively　insensitive　to　the　thickness　of　the　active　layer　and　exhibited　good　stability.