widely used electron acceptor materials since the first report by Wudl and co-workers. [6] Recently, nonfullerene smallmolecule acceptors have been developed as alternatives to fullerene derivatives, offering advantages of good stability, easily tunable energy levels, and broadband absorption range. [7][8][9][10][11][12][13][14][15][16][17][18][19] In 2015, Zhan and co-workers synthesized a planar nonfullerene electron acceptor 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5, 11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d: 2 0 ,3 0 -d 0 ]-s-indaceno[1,2-b:5,6-b 0 ]dithiophene (ITIC) and used it in OSCs with a record PCE for nonfullerene OSCs at that moment. [20] In 2016, Hou and co-workers reported a new type of high-efficiency nonfullerene OSCs based on poly [(2,6-(4,8bis(5-(2-ethylhexyl)ITIC with PCE up to 11.2% and excellent thermal stability. [21] After fluorination of the organic semiconductors, they further enhanced the PCE of OSCs up to over 13% based on PBDB-T-SF:IT-4F. [22] Nowadays, a new acceptor material Y6 was synthesized by Zou and co-workers exhibiting a high charge carrier mobilities and a broad absorption range from 400 to 950 nm. As a result, a new PCE record of 15.7% has been realized when they incorporated Y6 with PM6 in OSCs. [23] Notably, PCEs of OSCs are still lower than those of OSCs because of the low carrier mobilities and short exciton diffusion lengths in organic semiconductors. [24] One feasible approach is to introduce additives such as plasmonic nanoparticles, [25][26][27][28] 2D materials, [29][30][31][32][33][34] and high mobility polymers [35] in OSCs to enhance light absorption as well as carrier transportation in the devices. We have demonstrated the successful additions of black phosphorus quantum dots, Au/Ag core-shell nanocuboids, and high-mobility conjugated polymers into OSCs based on PTB7:PC 71 BM or poly [4,8-bis(5-(2-ethylhexyl)thiophen-2-yl) benzo [1,2-b;4,5-b 0 ]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PBDTTT-EFT):PC 71 BM, [25,29,35,36] and the PCEs of the devices were all improved relatively for over 10%. In addition to the enhanced light absorption and carrier transfer in BHJ active layers induced by the additives, the morphological change of BHJ can be another critical issue to the device performance. In this regard, the
