Efficient Organic Solar Cells Based on Planar Metallophthalocyanines

Abstract

Organic solar cells based on planar metallophthalocyanines (MPc, M = Cu, Zn, Pd, Pc)/3,4,9,10-perylene tetracarboxylic bisbenzimidazole (PTCBI) were investigated. PdPc/PTCBI solar cells have a peak external quantum efficiency of 30.9%, which is almost twice as those of conventional solar cells based on CuPc and ZnPc/PTCBI. Optical modeling was carried out using a transfer matrix algorithm in order to determine the exciton diffusion lengths for four MPcs. External quantum efficiency measurement and optical modeling indicate that PdPc has the longest exciton diffusion length among four different MPcs, leading to a power conversion efficiency of 1.3% and a short circuit current density of 4.0 mA/cm2 under the illumination of AM 1.5 G 100 mW/cm2. When fullerene (C60) was used as an acceptor, solar cells based on PdPc exhibit a short circuit current density of 6.8 mA/cm2, resulting in a power conversion efficiency of 2.2%, while solar cells based on CuPc show 1.6%.

Layer‐by‐Layer Processed Organic Solar Cells

“…In 2001, Forrest and Peumans fabricated bilayer heterojunction OPVs based on CuPc and C 60 with a PCE of 3.6% under 150 mW cm −2 simulated AM1.5G illumination. [47] SubPc/C 60 OPVs exhibited much higher V OC (0.97 V) as compared to CuPc/C 60 -based devices, resulting in an enhancement of PCE from 0.9 to 2.1%. [71] By systematically tuning energy level, a bilayer OPV based on subnaphthalocyanine chloride (SubNc) donor and hexachlorinated SubPc (Cl 6 -SubPc-Cl) acceptor achieved a PCE as high as 6.86% and a V OC of 1.04 V. [70] The optimized bilayer device based on MC dye ID583/C 60 showed PCE up to 3.9% with a high FF of 0.70.…”

“…[22] The mixed interlayer was recognized as the first bulk heterojunction layer in small molecule-based OPVs. In 1992, Sariciftci et al demonstrated that photoexcitation of a mixture of a conjugated polymer and fullerene (C 60 ) resulted in an ultrafast, highly efficient photoinduced electron transfer. [23] In 1995, Heeger et al created the bulk heterojunction (BHJ) concept, which refers to a blend of bicontinuous and interpenetrating donor and acceptor components in a bulk volume.…”

Optical Constants of α‐ and β‐Zinc(II)‐Phthalocyanine Films

“…It has already been applied in prototypes of solar cells [1][2][3][4]. Furthermore, it is already known that phthalocyanines (including ZnPc) can exist in multiple types of crystalline phases [5]; in particular, the metastable -ZnPc (higher electrical conductivity) and the stable -ZnPc (lower electrical conductivity) [6] need to be distinguished.…”

Enhanced power conversion efficiency of p-i-n type organic solar cells by employing a p-layer of palladium phthalocyanine

“…Recently, we have reported that replacement of centered metal ions with palladium in widely used planar metallophthalocyanines ͑MPcs͒ such as CuPc and ZnPc resulted in a longer exciton diffusion length. 6 In this article, we report the enhancement of PCE in p-i-n type solar cells of ZnPc and C 60 by substituting palladium phthalocyaine ͑PdPc͒ for the ZnPc p-layer. In addition, charge carrier collection efficiency in mixed layers of MPc and C 60 is also discussed.…”

“…This stems from a longer exciton diffusion length in PdPc ͑ϳ10 nm͒ compared to ZnPc ͑ϳ6 nm͒. 6 Insertion of a mixed i-layer of ZnPc: C 60 leads to enhancement in PCE ͑A-and C-type cells͒. The PCE increases with increasing thickness of the mixed layer up to 20 nm.…”