Life Beans Center Kyushu

Fukuoka-shi, Japan

Life Beans Center Kyushu

Fukuoka-shi, Japan

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Hirade M.,Kyushu University | Hirade M.,Life Beans Center Kyushu | Nakanotani H.,Kyushu University | Nakanotani H.,Life Beans Center Kyushu | And 6 more authors.
ACS Applied Materials and Interfaces | Year: 2011

To enhance the performance of organic photovoltaic (OPV) cells, preparation of organic nanometer-sized pillar arrays is fascinating because a significantly large area of a donor/acceptor heterointerface having continuous conduction path to both anode and cathode electrodes can be realized. In this study, we grew cupper phthalocyanine (CuPc) crystalline nanopillar arrays by conventional thermal gradient sublimation technique using a few-nanometer-sized trigger seeds composed of a CuPc and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) stacked layer. We optimized the pillar density by tuning crystal growth condition in order to apply it to OPV cells. © 2011 American Chemical Society.


Zou Y.,Kyushu University | Zou Y.,Beijing Jiaotong University | Deng Z.,Beijing Jiaotong University | Potscavage W.J.,Kyushu University | And 6 more authors.
Applied Physics Letters | Year: 2012

Organic solar cells (OSCs) based on chloroaluminum phthalocyanine (ClAlPc) as donor and fullerene C 60 as acceptor with a multi-tandem structure were fabricated. We demonstrated very high open-circuit voltage (V OC) and enhanced power conversion efficiency (PCE) for the multi-tandem OSCs. Using a fivefold structure, we obtained PCE of 2.49% with a V OC of 3.50 V, in comparison with PCE of ∼2 and V OC of 0.72-0.81 V for the single device. We also fabricated a tenfold-stacked OSC showing an extremely high V OC of 5.89 V. The multi-tandem OSCs with very high V OC have great potential for applications in limited-area low-power electronics. © 2012 American Institute of Physics.


Hirade M.,Kyushu University | Hirade M.,Life Beans Center Kyushu | Adachi C.,Kyushu University | Adachi C.,Life Beans Center Kyushu
Applied Physics Letters | Year: 2011

We demonstrate enhanced power conversion efficiency (PCE) for small molecular-based organic photovoltaic cells with an exciton blocking layer (ExBL) at the anode/donor interface. Although poly(3,4-ethylenedioxythiophene): poly(4-styrene sulfonate) (PEDOT:PSS) films are widely used as anodic buffer layers, they also act as exciton quenchers. To prevent exciton quenching, we introduced a tris[4-(5-phenyl thiophen-2-yl)phenyl]amine layer between the donor and the PEDOT:PSS layer and clarified its effect. By a combination of dual ExBLs at both the anode and cathode sides, we achieved significantly enhanced short circuit current and PCE values; the highest PCE 5.24 was obtained by optimizing the device parameters. © 2011 American Institute of Physics.


Zheng Y.-Q.,Kyushu University | Zheng Y.-Q.,Life Beans Center Kyushu | Potscavage Jr. W.J.,Kyushu University | Komino T.,Kyushu University | And 2 more authors.
Applied Physics Letters | Year: 2013

Efficient bulk heterojunction (BHJ) photovoltaic cells (PVs) based on 5 wt. donors and C70 were fabricated. Tris[4-(5-phenylthiophen-2-yl) phenyl]-amine (TPTPA)-based BHJ PVs show higher power conversion efficiency (ηPCE) than aluminum phthalocyanine chloride-based BHJ PVs. Although the absorption of AlPcCl is complementary to that of C70, TPTPAs high hole mobility and symmetrical molecular structure are likely to be crucial contributing factors to the higher ηPCE. Phase separation occurs in the 5-TPTPA blend. The device was optimized via replacement of the bathocuproine buffer by a combination of 3,4,9,10-perylenetetracarboxylic bis-benzimidazole and bathocuproine. ηPCE of 5.96 is achieved because of the decreased series resistance. © 2013 AIP Publishing LLC.


Zheng Y.-Q.,Kyushu University | Zheng Y.-Q.,Life Beans Center Kyushu | Potscavage W.J.,Kyushu University | Komino T.,Kyushu University | And 5 more authors.
Applied Physics Letters | Year: 2013

Highly efficient photovoltaic cells based on a bulk heterojunction configuration composed of C70 with various donor materials at 5 wt.% donor concentration were fabricated. The tetraphenyldibenzoperiflanthene (DBP) donor achieved the highest power conversion efficiency (ηPCE) of 6.4% for the optimized cell. The improved performance with DBP arises from a combination of a higher absorption coefficient than 1,1-bis-(4-bis(4-methyl- phenyl)-amino-phenyl)-cyclohexane and a symmetrical molecular structure. The high ηPCE with only 5 wt. donor is attributed to a sufficient donor concentration for enhanced Frenkel exciton dissociation in C70, while efficiency and electron mobility decrease at higher donor concentrations. © 2013 AIP Publishing LLC.

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