| dc.description.abstract | Organic Photovoltaics (OPVs) have been attracted lots of attention because of the flexibility, lightweight and low fabrication cost. There are two main approaches used to improve the power conversion efficiency (PCE) of OPVs: adding additive in the active layers or adding third component in the active layer to fabricate ternary solar cell.In this thesis, the two series of compounds (small molecules and polymers), which were synthesized in our group, were used in OPVs as the donor or additive. For the diketopyrrolopyrrole based small molecule (SM), the highest PCE of the inverted SM2:PCBM based photovltaics with an additive of the 1,8-diiocooctane (1-chloronaphathalene) was 0.71% (0.29%). In the SM2:P3HT:PCBM (0.1:0.9:1 wt%) based ternary solar cells, a moderate PCE of 3.30% can be achieved. For the benzodithiophene based polymers (P8, P10, P11), the optimal PCE of the inverted P11/PC61BM based solar cells is 3.48%. The PCE of the P11/PC61BM based solar cells is 3.48% when the 1,8-diiocooctane (1 vol%) is added as the additive.There is a universal spin rate (~ 1000 rpm) for the fabrications of the active layer for SM molecules and polymers. The optimal thermal annealing conditions for the active layer based on SM molecules and polymers are not tha same. There is no a rule that can be obeyed to find out the optimized donor/acceptor ratio and concentration of the active layers. It is notice that the optimal PCE of the all solar cells can be achieved when the 1,8-diiocooctane (1 vol%) is used as the additive but no optimal concentration for the 1-chloronaphathalene additive. | en_US |