Co-sensitization of metal free organic dyes in flexible dye sensitized solar cells

Lee, Horim,Kim, Jihun,Kim, Dong Young,Seo, Yongsok Elsevier 2018 ORGANIC ELECTRONICS Vol.52 No.-

<P><B>Abstract</B></P> <P>A metal-free organic dye (JH-1) and an unsymmetrical squaraine dye (SQ2) were used for co-sensitization of a flexible TiO<SUB>2</SUB> electrode in order to obtain a broad spectral response in the visible light regions. Because of enhanced light absorption, the performance of the flexible plastic dye-sensitized solar cells (DSSCs) was enhanced. The dye concentration of co-sensitized TiO<SUB>2</SUB> film was higher than that of individual dye-sensitized TiO<SUB>2</SUB> film, leading to improved photovoltaic performance with the panchromatic light harvesting of JH-1 and SQ2 (350–720 nm). Optimum molar ratio of individual dye, dye concentration and adsorption kinetics onto the TiO<SUB>2</SUB> photoelectrode, and ideal thickness of HS-TiO<SUB>2</SUB> layer have been investigated. A flexible DSSC co-sensitized with the molar ratio of 60:40 (JH-1:SQ2) and TiO<SUB>2</SUB> film thickness of 6 μm yielded a high photocurrent density of 12.32 mA cm<SUP>−2</SUP>, an open circuit voltage of 0.754 V, a fill factor of 0.68, and a power conversion efficiency of 6.31% under 1 sun illumination (100 mW cm<SUP>−2</SUP>). Interestingly, the co-sensitizers did not compete with each other for the absorption. Both the open circuit photovoltage and the photocurrent density were unexpectedly increased with co-sensitization which means that enhancement in photocurrents can be achieved without sacrificing the open circuit photovoltage for the co-sensitized solar cells, once the electron recombination and dye aggregation are retarded by the co-sensitization.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An organic dye (JH-1) and a squaraine dye (SQ2) were used for co-sensitization of a flexible TiO2 electrode. </LI> <LI> Because of enhanced light absorption, the performance of the flexible DSSCs was enhanced. </LI> <LI> A DSSC with a molar ratio of 60:40 (JH-1:SQ2) yielded a power conversion efficiency of 6.31%. </LI> <LI> Both V<SUB>OC</SUB> and J<SUB>SC</SUB> were unexpectedly increased with co-sensitization. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Dye-Sensitized Tandem Solar Cells with Extremely High Open-Circuit Voltage Using Co(II)/Co(III) Electrolyte

Choi, Won Seok,Choi, In Taek,You, Ban Seok,Yang, Ji-Woon,Ju, Myung Jong,Kim, Hwan Kyu LASER PAGES PUBLISHING LTD 2015 ISRAEL JOURNAL OF CHEMISTRY Vol.55 No.9

<P> For achieving a high open-circuit voltage (V<SUB>oc</SUB>) in dye-sensitized tandem solar cells, series-connected tandem solar cells were fabricated. In order to optimize series-connected tandem solar cell systems, the current density of the top and bottom cells should be well matched to be identical, and the V<SUB>oc</SUB> of each of the cells should also be as high as possible. Furthermore, the top cell should be transparent and the bottom cell should have the longer-wavelength absorption, for utilizing only the light passing through the top cell. This leads to a high V<SUB>oc</SUB>. In this study, we report dye-sensitized tandem solar cells having an extremely high V<SUB>oc</SUB> using the Co(bpy)<SUB>3</SUB><SUP>2+/3+</SUP> (bpy=2,2′-bipyridine) redox couple. Dye-sensitized tandem solar cells employing JK303/HC-A1 with the Co(bpy)<SUB>3</SUB><SUP>2+/3+</SUP> redox couple as the top cell and N749/HC-A4 with the I-/I<SUB>3</SUB>- redox couple as the bottom cell were shown to have an extremely high V<SUB>oc</SUB> of >1.66V, the highest value for dye-sensitized tandem solar cells reported to date. </P>

은 나노 입자를 이용한 염료감응형 태양전지의 효율 향상 효과

정행윤,홍경진 한국전기전자재료학회 2018 전기전자재료학회논문지 Vol.31 No.1

In this study, e-beam equipment was used to form silver nanoparticles on thin films of TiO2 to increase theefficiency of dye-sensitized solar cells and improve the annealing process. TiO2 thin films with nanoparticlephotoelectrodes were fabricated in individual units for use in dye-sensitized solar cells. The characteristics ofdye-sensitized solar cells were compared to those of the prepared TiO2 photoelectrode with and without nanoparticles. The dye-sensitized solar cells with silver nanoparticles showed a significant increase in the electric current densitycompared with the pure TiO2 dye-sensitized solar cell and improved the solar conversion efficiency to 27.89%. Theincreased density of electric current increased the extent of light absorption of the dye owing to the plasmon resonanceof the nanoparticles at the local surfaces. This phenomenon led to increased light scattering, which in turn increased thecurrent density of the dye-sensitized solar cells and improved the solar conversion efficiency. 본 연구에서는 염료감응형 태양전지의 광전변환효율을 증가시키기 위해 TiO2 박막 위에 은 나노 입자를 형성하고자 E-beam 장비를 이용하였고, 어닐링 공정을 진행하였다. 은 나노 입자들이 형성된 TiO2 박막을 광전극으로 사용하였으며 염료감응형 태양전지 단위 셀을 제작하였다. 은 나노 입자들이 포함 된 TiO2 광전극과 순수한 TiO2 광전극을 사용한 염료감응형 태양전지를 비교하여 특성을 분석하였다. 은 나노 입자들이 포함 된 염료감응형 태양전지는 순수한 TiO2 염료감응형 태양전지에 비해 전류 밀도의 상당한 증가를 가져왔으며 광전변환효율이 최대 27.89% 개선되는 것으로 나타났다. 전류 밀도의 증가는 은 나노 입자들의 국소적 표면 플라즈몬 공명으로 인한 염료의 광흡수를 증가시켜 광 산란의 강화로 인해 염료감응형 태양전지의 전류밀도와 광전변환효율을 증가시켰다.

Enhanced Performance of Dye Co-sensitized Solar Cells by Panchromatic Light Harvesting

김영록,Hyun Sik Yang,안광순,김재홍,한윤수 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.6

The Photovoltaic properties of dye co-sensitized solar cells fabricated by using a onebathmixed dye solution were compared with those of mono-sensitized devices. Co-sensitizedTiO2 photo-electrodes were prepared from a mixed dye solution of M-Red [2-cyano-3(10-hexthyl-phenothiazin)acrylic acid] or D-Red [3,3’-hexyl-bis(phenothiazine-2-cyanoacrylic acid)]and S-Blue [(5-carboxy-3,3-dimethyl-1-nonyl-indolium)methylene-2-(E)-(5-carboxy-3,3-dimethyl-1-octylindolin-2-ylidene)-3-oxocyclobut-1-enolate)] to improve the short-circuit current (Jsc) of dyesensitizedsolar cells (DSSCs). When the photo-electrode was co-sensitized from the mixed solutionof M-Red (75%) and S-Blue (25%), the power conversion efficiency (PCE) of the resulting DSSCsexhibited an 11.2% increase, compared to that of M-Red dye (100%). Use of the mixed dye solutionof M-red and S-Blue is thought to have ability to reduce the aggregation of S-Blue dye adsorbedon TiO2 surface, leading to an enhancement in Jsc of the co-sensitized solar cells. In the case ofD-Red dye, the co-sensitized device prepared from the mixed solution of D-Red (50%) and S-Blue(50%) dye showed a 31.7% enhancement in the PCE, compared to that of the solar cell with a mono(D-Red)-sensitized photo-electrode. Unlike the co-sensitization system using the mixed solution ofM-Red and S-Blue, the optimum photovoltaic performance was found from the mixed solution witha 1:1 ratio (D-Red:S-Blue). This could be attributed to the adsorption rate of D-Red (dimeric red)being faster than that of M-Red (monomeric red) dye, there inducing similar adsorption rates forthe D-Red and the S-blue dye in the one-bath adsorption process for co-sensitization.

염료감응 태양전지

박남규 한국공업화학회 2004 공업화학 Vol.15 No.3

빛에너지를 전기에너지로 직접 변환 시키는 태양전지는 구성하는 물질에 따라 무기물 태양전지와 유기물 태양전지로 나눌 수 있다. 무기물 태양전지는 실리콘, 화합반도체 등의 소재가 pn 접합으로 구성되어 있으며, 유기물 태양전지는 염료분자가 나노결정 입자 표면에 흡착되어 있는 것을 특징으로 하는 염료감응형과 donor-acceptor 특성의 유기(고)분자형으로 나눌 수 있다. 특히 염료감응형 유기태양전지는 높은 에너지변환 효율(약 11%)과 매우 낮은 제조가격 때문에 차세대 태양전지로 각광받고 있다. 본 총설에서는 염료감응 태양전지의 구조 및 작동원리를 설명하고, 최근의 연구개발 및 산업동향을 소개하였다. Solar cells, converting directly light into electricity, can be categorized by materials comprising solar cells: inorganic-type and organic-type solar cells. Inorganic solar cells are composed of inorganic n-type and p-type materials such as silicon and compound semiconductors, where the structure of inorganic solar cell is typically built by pn junction. For the organic solar cells, there are two types: dye-sensitized solar cell and organic donor-acceptor solar cell. Dye-sensitized solar cell, consisting of nanocrystalline oxide film sensitized with dye molecule, redox electrolyte and metal counter electrode, is consideed as alternative to conventional solar cells due to its high solar-to-electricity conversiton efficiency (ca. 11%) and low cost. In this article, the structure, the operation principle and the recent R&D and industrial trends of dye-sensitized solar cells are discussed.

Sputtered ZTO as a blocking layer at conducting glass and TiO₂ Interfaces in Dye-Sensitized Solar Cells

박재호(Park, Jaeho),이경주(Lee, Kyungju),송상우(Song, Sangwoo),조슬기(Jo, Seulki),문병무(Moon, Byungmoo) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.11

Dye-sensitized solar cells(DSSCs) have been recognized as an alternative to the conventional p-n junction solar cells because of their simple fabrication process, low production cost, and transparency. A typical DSSC consists of a transparent conductive oxide (TCO) electrode, a dye-sensitized oxide semiconductor nanoparticle layer, liquid redox electrolyte, and a Pt-counter electrode. In dye-sensitized solar cells, charge recombination processes at interfaces between coducting glass, TiO₂, dye, and electrolyte play an important role in limiting the photon-to-electron conversion efficiency. A layer of ZTO thin film less than ~200nm in thickness, as a blocking layer, was deposited by DC magnetron sputtering method directly onto the anode electrode to be isolated from the electrolyte in dye-sensitized solar cells(DSCs). This is to prevent the electrons from back-transferring from the electrode to the electrolyte (I^-/I₃^-). The presented DSCs were fabricated with working electrode of Ga-doped ZnO glass coated with blocking ZTO layer, dye-attached nanoporous TiO₂ layer, gel electrolyte and counter electrode of Pt-deposited GZO glass. The effects of blocking layer were studied with respect to impedance and conversion efficiency of the cells.

Co-sensitization of N719 with an Organic Dye for Dye-sensitized Solar Cells Application

Wu, Zhisheng,Wei, Yinni,An, Zhongwei,Chen, Xinbing,Chen, Pei Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.5

The co-sensitization of N719 with a cyclic thiourea functionalized organic dye, coded AZ5, for dye-sensitized solar cells (DSSCs) was demonstrated. Due to its intensive absorption in ultraviolet region, AZ5 could compensate the loss of light harvest induced by triiodide, thereby the short-circuit photocurrent density ($J_{sc}$) was increased for co-sensitized (N719+AZ5) DSSC. Moreover, the electron recombination and dye aggregation were retarded upon N719 cocktail co-sensitized with AZ5, thus the open-circuit voltage ($V_{oc}$) of co-sensitized device was enhanced as well. The increased $J_{sc}$ (17.9 $mA{\cdot}cm^{-2}$) combined with the enhanced $V_{oc}$ (698 mV) ultimately resulted in an improved power conversion efficiency (PCE) of 7.91% for co-sensitized DSSC, which was raised by 8.6% in comparison with that of N719 (PCE = 7.28%) sensitized alone. In addition, co-sensitized DSSC exhibited a better stability than that of N719 sensitized device probably due to the depression of dye desorption.

Syntheses of Organic Dyes Based on Phenothiazine as Photosensitizers and Effects of Their π-Conjugated Bridges on the Photovoltaic Performances of Dye-Sensitized Solar Cells

김기현,김미라,이승민,서민혜,조상은,황원필,박성해,김영근,이진국 한국고분자학회 2012 Macromolecular Research Vol.20 No.2

Three organic dyes, 2-cyano-3-(N-hexylphenothiazine-3-yl)acrylic acid (H-PTZ), 2-cyano-3-(5'-(2-(Nhexylphenothiazine-3-yl)vinyl)-2,2'-bithiophen-5-yl)acrylic acid (H-PTZ-BT), and 2-cyano-3-(5-(4-((4-(2-(N-hexylphenothiazine-3-yl)vinyl)phenyl)(phenyl)amino)phenyl)thiophen-2-yl)acrylic acid (H-PTZ-TPA-T), based on the phenothiazine (PTZ) unit as an electron donor moiety and cyanoacrylic acid unit as an electron acceptor moiety were synthesized to study the effect of a π-conjugated bridge of the dye on the performance of the resulting dye-sensitized solar cells devices. The thiophene unit and triphenylamine were introduced as a π-conjugated bridge. The H-PTZTPA-T–sensitized cell showed the highest overall conversion efficiency of 4.01% (Jsc: 9.64 mA·cm-2; Voc: 0.69 V;FF: 0.60), while the H-PTZ-sensitized cell showed the lowest value of 3.57% (Jsc: 7.76 mA·cm-2; Voc: 0.70 V; FF:0.65) among the cells based on the three organic dyes compared to 5.09% for the cell based on the N719 dye (Jsc:12.77 mA·cm-2; Voc: 0.72 V; FF: 0.55) under AM 1.5 illumination (100 mW·cm-2).

Dye-sensitized solar cell and electrochemical supercapacitor applications of electrochemically deposited hydrophilic and nanocrystalline tin oxide film electrodes

Rajaram S. Mane,장진호,Dukho Ham,B.N. Pawar,T. Ganesh,한성환,이준기,조병원 한국물리학회 2009 Current Applied Physics Vol.9 No.1

The present article demonstrates the use of low-cost electrochemically synthesized hydrophilic and nanocrystalline tin oxide film electrodes at room temperature in dye-sensitized solar cells and electrochemical supercapacitors. A mixed phase of tin instead of single phase composed of uniformly distributed irregular spherical grains in a nanometer regime scale was obtained. Tin oxide film electrode showed efficient photoperformance when subjected to dye-sensitized solar cells. The interfacial and specific capacitances of 118.4 μF/㎠ and 43.07 F/g, respectively, in 0.1 M NaOH electrolyte were confirmed from cyclic-voltammetry measurement. The present article demonstrates the use of low-cost electrochemically synthesized hydrophilic and nanocrystalline tin oxide film electrodes at room temperature in dye-sensitized solar cells and electrochemical supercapacitors. A mixed phase of tin instead of single phase composed of uniformly distributed irregular spherical grains in a nanometer regime scale was obtained. Tin oxide film electrode showed efficient photoperformance when subjected to dye-sensitized solar cells. The interfacial and specific capacitances of 118.4 μF/㎠ and 43.07 F/g, respectively, in 0.1 M NaOH electrolyte were confirmed from cyclic-voltammetry measurement.

Density functional theory study on ruthenium dyes and dye@TiO₂ assemblies for dye sensitized solar cell applications

Chitumalla, Ramesh Kumar,Jang, Joonkyung Elsevier Science B.V., Amsterdam. 2018 SOLAR ENERGY -PHOENIX ARIZONA THEN NEW YORK- Vol.159 No.-

<P><B>Abstract</B></P> <P>Cyclometalated ruthenium dyes improve significantly the performance of dye sensitized solar cells (DSSCs) based on conventional ruthenium dyes. Here, this study examined four thiocyanate-free cyclometalated ruthenium dyes using the density functional theory (DFT). The geometrical, electronic structural, and photophysical propertiesof the dyes and the dyes tethered to a TiO<SUB>2</SUB> surface were examined in both the presence and absence of an acetonitrile solvent. The Kohn-Sham eigenvalues of the molecular orbitals of the dyes were destabilized by <I>ca</I>. 2 eV in the presence of the solvent. The absorption peaks did not change significantly in position but hyperchromic shifts of more than two-fold occurred. When adsorbed on a TiO<SUB>2</SUB> surface, the dyes showed redshifted absorption of approximately 20 nm. To the best of our knowledge, a systematic and comprehensive first-principles investigation on cyclometalated ruthenium dyes in vacuum, solvent, and tethered to TiO<SUB>2</SUB> has been carried out for the first time.</P> <P><B>Highlights</B></P> <P> <UL> <LI> DFT study on cyclometalated Ru dyes in gas phase, solution, and on TiO<SUB>2</SUB>. </LI> <LI> Investigation of solvent effect on dyes and dye-sensitized TiO<SUB>2</SUB>. </LI> <LI> Destabilization of molecular orbitals of the dyes by 2 eV upon solvation. </LI> <LI> Dyes showed more than twofold hyperchromic shift in absorption in the solvent. </LI> <LI> Upon adsorption on TiO<SUB>2</SUB>, the dyes have shown a redshift of 20 nm in the absorption. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>The dye interaction with solvent causes significant variations in their physical and chemical properties. The solvent in dye sensitized solar cells strongly affects the device efficiency and stability. The present study investigates the effect of acetonitrile solvent on the structural, electrochemical, and optical properties of four cyclometalated ruthenium dyes and dye@TiO<SUB>2</SUB> assemblies employing DFT/TDDFT and periodic-DFT methods. This study also investigates how anchoring of the dye on TiO<SUB>2</SUB> surface affects their electrochemical and photophysical behavior.</P> <P>[DISPLAY OMISSION]</P>