Selective Dye Loading at the Heterojunction in Polymer/Fullerene Solar Cells

Abstract

Selective dye loading at the polymer/fullerene interface was studied for ternary blend bulk heterojunction solar cells, consisting of regioregular poly(3-hexylthiophene) (RR-P3HT), a fullerene derivative (PCBM), and a silicon phthalocyanine derivative (SiPc) as a light-harvesting dye. The photocurrent density and power conversion effi ciency of the ternary blend solar cells were most improved by loading SiPc with a content of 4.8 wt%. The absorption and surface energy measurements suggested that SiPc is located in the disordered P3HT domains at the RR-P3HT/PCBM interface rather than in the PCBM and crystal P3HT domains.

Fabrication and characterization of P3HT:PCBM-based thin film organic solar cells with zinc phthalocyanine

“…The values of the conduction band or lowest unoccupied molecular orbital (LUMO) for P3HT, ZnPc and PCBM are -3.1 eV, -3.5 eV and -3.7 eV, respectively. Since the LUMO value of the ZnPc is between those of P3HT and PCBM, electrons could transport from P3HT to PCBM [16]. The IPCE values in the range of 300-650 nm were increased by the ZnPc addition, which could be explained by the Förster energy transfer from the P3HT to ZnPc.…”

“…Interfacial structure models and an energy level diagram of the present P3HT:PCBM:ZnPc solar cell are summarized and illustrated, as shown in Figures 7 and 8, referring the previous models and mechanisms [3,[15][16][17][18][19]. For the cell with the inverted structure, electrons are transported to an ITO substrate, and holes are transported to an Au electrode.…”

“…Since phthalocyanines absorb near-infrared light, the effects of addition of silicon phthalocyanine, silicon naphthalocyanine or germanium phthalocyanine to the P3HT:PCBM system were investigated [15][16][17][18][19][20][21]. Solubilized metal phthalocyanines (MPc) could be dissolved in organic solvents, and the application for the device process using a spin-coating method could be expected.…”

Insights into photovoltaic properties of ternary organic solar cells from phase diagrams

“…Already in binary blend systems, a highly optimized morphology is necessary to efficiently generate and extract charge carriers. Ternary blends can form an even larger variety of morphologies, depending on the ratio and the interactions between the components [2,17]. The complexity of the system is substantially increased.…”

“…Several studies have shown that adding a third component up to a certain amount leads to an increase in the efficiency, followed by a drop at higher loadings. This drop is often reasoned to be due to a change in the morphology [10,17,30]. This dependence makes it necessary that electro-optical properties and morphology are synchronized and it can be hypothesized that controlling the morphology is the key to obtain high performance ternary blend solar cells [30–35].…”