金纳米四面体增强有机太阳电池光吸收及光伏性能研究

为增强有机太阳能电池的光利用率,提高能量转换效率,本文合成了金四面体形状的纳米粒子,并用聚苯乙烯磺酸钠(PSS)包裹形成了核壳结构的金纳米四面体(Au@PSS tetrahedra NPs).将其掺杂到有机太阳能电池空穴提取层与活性层的界面处,利用表面等离子体共振效应来增强活性层对光的吸收,从而提高有机太阳能电池的能量转换效率.研究了掺杂浓度和PSS包裹厚度对电池性能的影响.结果表明:掺杂浓度为6%时,器件性能最佳,能量转换效率达到3.08%; PSS壳层厚度优化为2.5 nm时,转换效率达到3.65%,较标准电池提升了22.9%.电池性能的改善主要源于金四面体纳米粒子的共振吸收峰位于给体材料吸收谱范围内,纳米粒子的共振促进了给体的吸收,同时PSS壳层的引入促进了激子的解离和电荷的转移,上述因素的改善提升了电池的短路电流、填充因子和转换效率.

Enhanced light absorption and device performances of organic photovoltaic devices with Au tetrahedra nanoparticles

Organic photovoltaic devices (OPVs) have attracted considerable attention because of their advantages of light-weight, low-cost, large-scale manufacturing process and mechanical flexibility. Unfortunately, in order to achieve efficient carrier extraction, the photoactive layer in OPVs must be rather thin (100 nm or less) due to its extremely low carrier mobilities for most of organic/polymer materials (on the order of 10^-4 cm²/(V·s)). Such thin photoactive layers lead to a significant loss of incident sunlight, thereby improving a final low light absorption efficiency and power conversion efficiency (PCE). To promote the light absorption and thus enhance PCE of OPVs, Au tetrahedron nanoparticles (NPs) are synthesized in this work and then they are wrapped with poly (sodium 4-styrenesulfonate) (PSS) to form core-shell structure tetrahedron NPs (Au@PSS tetrahedron NPs). They are further incorporated into the interface of hole extraction layer and light photoactive layer to improve PCE of OPVs by enhancing their surface plasmon resonance effect-induced light absorption. The influences of doping concentration and PSS shell thickness of theses Au tetrahedron NPs on device performances are explored. The results indicate that the best performing PCE occurs at 6% concentration of Au@PSS tetrahedron NPs, reaching 3.08%, while it is further improved to 3.65% with an optimized PSS shell thickness of 2.5 nm, showing an enhancement factor of 22.9% compared with that of the control counterpart. The performance improvement of OPVs mainly originates from the promoted light absorption of donor due to the location of the resonant absorption peak of Au@PSS tetrahedron NPs in the absorption region of donor. Simultaneously, the introduction of the PSS shell promotes the dissociation of excitons and charge transfer. All of these contribute to the increasing of short-circuit current, fill factor and PCE of OPVs.