Browsing by Author "Tsai, Pei-Ting"

Now showing 1 - 14 of 14

13% Efficiency Hybrid Organic/Silicon-Nanowire Heterojunction Solar Cell via Interface Engineering
(2013-12-01)
Yu, Peichen
;
Tsai, Chia-Ying
;
Chang, Jan-Kai
;
Lai, Chih-Chung
;
Chen, Po-Han
Interface carrier recombination currently hinders the performance of hybrid organic silicon heterojunction solar cells for high-efficiency low-cost photovoltaics. Here, we introduce an intermediate 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAP() layer into hybrid heterojunction solar cells based on silicon nanowires (SINWs) and conjugate polymer poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS). The highest power conversion efficiency reaches a record 13.01%, which is largely ascribed to the modified organic surface morphology and suppressed saturation current that boost the open-circuit voltage and fill factor. We show that the insertion of TAP( increases the minority carrier lifetime because of an energy offset at the heterojunction interface. Furthermore, X-ray photoemission spectroscopy reveals that TAP( can effectively block the strong oxidation reaction occurring between PEDOT:PSS and silicon, which improves the device characteristics and assurances for reliability. These learnings point toward future directions for versatile interface engineering techniques for the attainment of highly efficient hybrid photovoltaics.
Blade-coated sol-gel indium-gallium-zinc-oxide for inverted polymer solar cell
(2016-11-01)
Lee, Yan-Huei
;
Tsai, Pei-Ting
;
Chang, Chia-Ju
;
Meng, Hsin-Fei
;
Horng, Sheng-Fu
The inverted organic solar cell was fabricated by using sol-gel indium-gallium-zinc-oxide (IGZO) as the electron-transport layer. The IGZO precursor solution was deposited by blade coating with simultaneous substrate heating at 120 degrees C from the bottom and hot wind from above. Uniform IGZO film of around 30 nm was formed after annealing at 400 degrees C. Using the blend of low band-gap polymer poly[(4,8-bis-(2-ethylhexyloxy)-benzo(1,2-b: 4,5-b')dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene-)-2-6-diyl)] (PBDTTT-C-T) and [6,6]-Phenyl C71 butyric acid methyl ester ([70] PCBM) as the active layer for the inverted organic solar cell, an efficiency of 6.2% was achieved with a blade speed of 180 mm/s for the IGZO. The efficiency of the inverted organic solar cells was found to depend on the coating speed of the IGZO films, which was attributed to the change in the concentration of surface OH groups. Compared to organic solar cells of conventional structure using PBDTTT-C-T: [70]PCBM as active layer, the inverted organic solar cells showed significant improvement in thermal stability. In addition, the chemical composition, as well as the work function of the IGZO film at the surface and inside can be tuned by the blade speed, which may find applications in other areas like thin-film transistors. (C) 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Efficient semitransparent organic solar cells with good color perception and good color rendering by blade coating
(2017-04)
Wong, Ying Qian
;
Meng, Hsin-Fei
;
Wong, Hin Yong
;
Tan, Ching Seong
;
Wu, Chen-Yu
This paper proposes high efficiency semitransparent organic solar cells (OSCs) with good color perception and good color rendering using blade coating technique. We investigate four different polymer blends and first fabricate small area devices with active area of 0.04 cm(2), followed by large area devices with active area of 10.8 cm(2). Two of the polymer blends, 2,6-Bis(trimethyltin)-4,8-bis(5-(2-ethylhexyl) thiophen-2-yl)benzo[1,2-b:4,5-b\']dithiophene:6,6-phenyl C71-butyric acid methyl ester (PBDTTT-CT:PC71BM) and poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b\'] dithiophene-2,6-diyl-alt-(4-( 2-ethylhexyl)-3-fluorothienof 3,4-b Ithiophene-)-2-carboxylate-2-6-diyl)]: PC71BM (PBDTT-EFT:PC71BM) show promising results. For small area devices, semitransparent PBDTIT-CT:PC71BM and semitransparent PBDTIT-EFT:PC71BM achieve a power conversion efficiency (PCE) of 5.2% (opaque PCE = 7.5%) and 5.6% (opaque PCE = 9.4%) respectively. For large area devices, they are found to produce a PCE of 3.8% (opaque PCE = 4.2%) and 5.3% (opaque PCE = 5.9%) respectively. Based on the CIE 1931 chromaticity diagram, semitransparent PBDTIT-CT:PCTIBM and semitransparent PBITITT-EFT:PCTIBM are located very close to the standard illuminant D65, indicating good color perception. As for color rendering, they demonstrate high color rendering index (CR1) of 95.4 and 87.1 respectively. These combined high performances indicate high-quality transmitted light, which is suitable for window application. (C) 2017 Published by Elsevier B.V.
Enhancing efficiency for additive-free blade-coated small-molecule solar cells by thermal annealing
(2016-10-01)
Tsai, Pei-Ting
;
Meng, Hsin-Fei
;
Chen, Yongsheng
;
Kan, Bin
;
Horng, Sheng-Fu
Blade coating was successfully applied to realise high-efficiency small-molecule organic solar cells (OSCs) with a solution-processed active layer comprising a small organic molecule DR3TBDTT with a benzo[1,2 -b: 4,5-b'] dithiophene (BDT) unit as the central building block as the donor and [6,6] -phenyl-C71 -butyric acid methyl ester (PC71BM) as the acceptor. Using chloroform as the solvent, a DR3TBDTT/PC71BM blend active layer without an additive was effectively formed through blade coating. The power conversion efficiency (PCE) of small organic molecule solar cells was enhanced by 3.7 times through thermal annealing at 100 degrees C. This method produces OSCs with a high PCE of up to 6.69%, with an open circuit voltage (V-oc) of 0.97 V, a short-circuit current density (J(sc)) of 12.60 mA/cm(2), and a fill factor (FF) of 0.55. (C) 2016 Elsevier B.V. All rights reserved.
High-efficiency polymer solar cells by blade coating in chlorine-free solvents
(2014-04-01)
Tsai, Pei-Ting
;
Tsai, Chia-Ying
;
Wang, Chun-Ming
;
Chang, Yu-Fan
;
Meng, Hsin-Fei
High-performance polymer cells are typically fabricated by employing toxic solvents such as dichlorobenzene and chlorobenzene. In this study, blade coating with the chlorine-free solvents toluene and xylene is applied to polymer solar cells that contained the low band-gap polymer PBDTTT-C-T blended with [6,6]-phenyl-C71-butyric acid methyl ester ([70]PCBM). The highest efficiencies of the cells fabricated in toluene and xylene solutions were 6.09% and 6.11%, respectively. Atomic force microscopy images show that the films formed by blade coating using toluene and xylene were extremely smooth, with roughness of only 1 nm. This blade coating has a rapid-drying in a few seconds without the long-running thermal or solvent annealing. The possibility of high-volume environmentally-friendly fabrication of efficient polymer solar cells with minimal material waste is thus demonstrated using a combination of chlorine-free solvents and blade coating. (C) 2014 Elsevier B.V. All rights reserved.
Highly efficient and stable organic solar cell modules processed by blade coating with 5.6% module efficiency and active area of 216 cm(2)
(2019-03-01)
Huang, Kuan-Min
;
Wong, Ying Qian
;
Lin, Man-Chun
;
Chen, Chao-Hsuan
;
Liao, Chung-Hung
In this study, an efficient and stable large-area blade-coated organic solar cell (OSC) module with an active area of 216 cm(2) (16 elementary cells connected in series) is demonstrated by combining appropriate thermal annealing treatment with the use of 4,4 '-(((methyl(4-sulphonatobutyl)ammonio)bis(propane-3,1-diyl))bis(dimethyl-ammoniumdiyl))bis-(butane-1-sulfonate) (MSAPBS) as the cathode interfacial layer. For the opaque device using poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b ']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-)-2-carboxylate-2-6-diyl)] (PBDTTT-EFT (PTB7-Th)):[6,6]-phenyl C-71-butyric acid methyl ester (PC71BM) blend film as the active layer, the power conversion efficiency (PCE) of 5.6% is achieved under AM 1.5G solar light illumination. Very encouragingly, our strategy can be applicable for semitransparent OSCs, and a remarkable PCE up to 4.5% is observed. To the best of our knowledge, the PCE of 5.6% for opaque device and 4.5% for semitransparent device represent the highest PCE ever reported for OSCs with the active area exceeding 100 cm(2). The devices also show an impressive stability under outdoor environment, where the efficiency decay is less than 30% for 60 days. Our findings can pave the way toward the development of organic solar cell modules with high performance and long-term stability.
Hybrid Carbon Nanotube/Silicon Schottky Junction Solar Cells
(2016-01-01)
Chen, Sih-Han
;
Lai, Yi-Chun
;
Tsai, Pei-Ting
;
Lin, Yi-Cheng
;
Lin, Yan-Nan
In this work, highly transparent and conductive multi-wall-carbon nanotubes (MW-CNTs) are employed to realize solution-processed, hybrid silicon (Si) Schottky -junction solar cells. We first describe the optimization of device structures on silicon wafers with nanowire and micro-pyramidal surface textures, and compare the device characteristics with those of hybrid cells based on Si and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT: PSS). The optimized processing conditions include the length of silicon nanowires, the annealing temperature, and the shading ratio of the frontal silver grids. It is found that the hybrid CNT cells outperform the hybrid PEDOT: PSS counterpart under individually optimized processing conditions due to better transparency and conductivity of CNTs than PEDOT: PSS. The best hybrid CNT cells, fabricated using a 14% grid shield ratio, 150 degrees C annealing temperature, and 150nm nanowire length, achieve a PCE of 11.90% and 13.82% in micro-pyramid and nanowire (NW) textured silicon, respectively, in contrast to 7.43% and 12.96% for hybrid PEDOT: PSS cells. To control the rear surface recombination, we further employ two solution-processed, small-molecule materials, Tris(8-hydroxyquinolinato) aluminium (Alq(3)) and 1,3-bis(2-(4-tert-butylphenyl)-1,3,4-oxadiazol- 5-yl) benzene (OXD-7) via a blade-coating technique between the silicon wafer and aluminum electrode. As a result, the PCE of hybrid CNT/Si NW solar cells is enhanced to 13.92% and 14.41% with the insertion of the Alq3 and OXD-7 rear interlayer, respectively. With the high power conversion efficiency (PCE), manufacturing Si-based solar cells at temperatures below 150 degrees C without high vacuum conditions not only significantly lowers the fabrication cost, but also enables the use of ultrathin substrates to save on the material cost for the future.
ITO-free inverted polymer solar cell on metal substrate with top-illumination
(2014-01-01)
Chen, En-Chen
;
Tsai, Pei-Ting
;
Tsai, Chia-Ying
;
Chang, Jung-Hao
;
Huang, Zheng-Yu
High-performance polymer solar cells are conventionally fabricated on the rigid and costly indium-tin-oxide (ITO) glass substrates, which are incompatible with the roll-to-roll process with low cost. This study shows that polymer solar cells can be made on ITO-free flexible stainless steel with only a moderate compromise in power conversion efficiency. A blend of poly (3-hexylthiophene) (P3HT) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) was used as the active material for the inverted structure. The bottom electrode was an alloy of Al and Au spontaneously formed from a bi-layer during thermal annealing of the active layer. This alloy had a low work function of 3.9 eV, and a high resistance to oxide formation throughout the entire process. Semi-transparent Ag was used as the top electrode. These solar cells on stainless steel had an efficiency of 2.6%. The majority of the loss came from the top electrode transmission at approximately 60%. This all-metal approach makes roll-to-roll polymer cell fabrication possible. (C) 2013 Elsevier B.V. All rights reserved.
Large-area organic solar cells by accelerated blade coating
(2015-07-01)
Tsai, Pei-Ting
;
Yu, Kai-Chieh
;
Chang, Chia-Ju
;
Horng, Sheng-Fu
;
Meng, Hsin-Fei
Large-area photovoltaic devices have been fabricated using the blade coating technique. In this study, the use of accelerated blade motion in this technique significantly improved the thickness uniformity of blade-coated layers of polymer solar cells on an A4 glass substrate. Two types of active layers, P3HT: PC61BM and POD2T-DTBT: PC71BM, were studied. For the P3HT: PC61BM film, a thickness of 221 +/- 14 nm was realised in a 12 x 15 cm(2) active region with a coating blade acceleration of 8 mm/s(2). For the POD2T-DTBT: PC71BM film, a thickness of 98 +/- 6 nm was realised with a coating blade acceleration of 10 mm/s(2). Ten cells, each measuring 0.9 cm x 12 cm and monolithically fabricated, were connected in series, yielding a total active area of 108 cm(2). The power conversion efficiency of the resulting 10-cell module was 2.66% and 3.64% for P3HT: PC61BM and POD2T-DTBT: PC71BM, respectively. The blade coating technique involving the accelerated blade motion is therefore useful for fabricating low-cost large-area organic solar cells, and it may be a promising alternative for the commercialisation of organic solar cells. (C) 2015 Elsevier B.V. All rights reserved.
Multilayer rapid-drying blade coating for organic solar cells by low boiling point solvents
(2014-06-01)
Chen, En-Chen
;
Tsai, Pei-Ting
;
Chang, Bo-Jie
;
Wang, Chun-Ming
;
Meng, Hsin-Fei
A bulk heterojunction organic solar cell with poly(3-hexylthiophene) (P3HT) as the donor and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor is deposited using blade coating on a hot plate at 80 degrees C with hot air of 70 degrees C applied from above. In contrast to the 30 min of conventional dichlorobenzene solvent annealing, the rapid-drying blade coating forms a dry film in 1 s. The fabrication throughput is substantially enhanced. The blade-coated film has a smoother surface roughness of 3.5nm compared with 10.5nm for solvent annealing; however, the desired phase separation in the 50nm scale forms despite the rapid drying. A single layer solar cell exhibits power conversion efficiency of 4.1% with blade coating in chlorobenzene, which is the same as solvent annealing device. A multilayer device with carrier blocking layers fabricated entirely of the less toxic toluene also exhibits efficiency of 4.1%. (C) 2014 The Japan Society of Applied Physics
Projected Efficiency of Organic/Inorganic Hybrid Tandem Solar Cells
(2013)
Chen, Po-Han
;
Huang, Yang-Yue
;
Pen, Huai-Te
;
Lai, Yi-Chun
;
Tsai, Chia-Ying
We propose a series-connected hybrid tandem solar cell which consists of an organic solar cell (P3HT/PCBM) as the top cell and an organic/crystalline silicon hybrid solar cell (PEDOT:PSS/c-Si nanowires) as the bottom cell. Based on the device structure, the organic materials can be directly spun-cast onto the inorganic silicon substrate with thermally evaporated metal contacts, making solution-based processes possible for rapid and low-cost production. With a proper design, the hybrid device architecture can achieve a high open-circuit voltage and junction-matched photocurrent, offering a promising approach for next-generation high-efficiency photovoltaics. In this work, we established a device model to investigate the photovoltaic characteristics of the proposed hybrid tandem solar cells by combining the organic and hybrid silicon solar cells with a hypothetic recombination layer (RL). First, the model of single junction solar cells is fitted to the current-voltage curve of fabricated devices. Next, we investigate the properties of the RL between the sub-cells and observe strong correlations with the photovoltaic performance of tandem cells. In our preliminary model, we have realized a cell with an open-circuit voltage (Voc), short-circuit current (Jsc), fill-factor (FF) and power conversion efficiency (PCE) of 1.093 V, 9.715 mAkm2, 43.725 % and 4.644 %, respectively. We will further tailor the properties of the RL, the active-layer thickness of sub-cells, as well as the band alignment, in order to achieve practical device designs. Currently, the characteristics of real hybrid tandem solar cells remain significantly lower than the simulation result. The reason of such limited cell performance is the poor interfacial contact, which makes it difficult to provide efficient recombination and transport for electrons and holes generated from sub-cells. A number of challenging issues, including interface physics and device design will be discussed.
Rear interface engineering of hybrid organic-silicon nanowire solar cells via blade coating
(2016-01-25)
Lai, Yi-Chun
;
Chang, Yu-Fan
;
Tsai, Pei-Ting
;
Chang, Jan-Kai
;
Tseng, Wei-Hsuan
In this work, we investigate blade-coated organic interlayers at the rear surface of hybrid organic-silicon photovoltaics based on two small molecules: Tris(8-hydroxyquinolinato) aluminium (Alq(3)) and 1,3-bis(2-(4-tert- butylphenyl)-1,3,4-oxadiazol-5-yl) benzene (OXD-7). In particular, soluble Alq3 resulting in a uniform thin film with a root-mean-square roughness < 0.2nm is demonstrated for the first time. Both devices with the Alq3 and OXD-7 interlayers show notable enhancement in the open-circuit voltage and fill-factor, leading to a net efficiency increase by over 2% from the reference, up to 11.8% and 12.5% respectively. The capacitance-voltage characteristics confirm the role of the small-molecule interlayers resembling a thin interfacial oxide layer for the Al-Si Schottky barrier to enhance the built-in potential and facilitate charge transport. Moreover, the Alq3 interlayer in optimized devices exhibits isolated phases with a large surface roughness, in contrast to the OXD-7 which forms a continuous uniform thin film. The distinct morphological differences between the two interlayers further suggest different enhancement mechanisms and hence offer versatile functionalities to the advent of hybrid organic-silicon photovoltaics. (C)2016 Optical Society of America
Solution p-doped fluorescent polymers for enhanced charge transport of hybrid organic-silicon nanowire photovoltaics
(2016-07)
Tsai, Pei-Ting
;
Li, Ming-Chin
;
Lai, Yi-Chun
;
Tseng, Wei-Hsuan
;
Wu, Chih-I
The solution p-type doping of various conjugated polymers and small molecules via blending with tetrafluorotetracyano-quinodimethane (F4-TCNQ) is investigated to facilitate hole transport for hybrid organic-silicon-nanowire solar cells. Among all, the highly-fluorescent conjugated polymers such as poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) demonstrate superior transport characteristics, where both the device fill-factor and power conversion efficiency (PCE) are positively correlated with the doping concentration. The best PCE achieves 13.66% from the device with 30% p-doped PFO, compared to the reference at 12.50%. The enhancement is ascribed to the efficient interfacial charge-carrier recombination with minimal energy losses. A vertically graded doping profile is further revealed with F4-TCNQ molecules preferentially accumulated near the silicon surface. (C) 2016 Elsevier B.V. All rights reserved.
Toward Long-Term Stable and Efficient Large-Area Organic Solar Cells
(2017-07-10)
Tsai, Pei-Ting
;
Lin, Kuan-Chu
;
Wu, Cheng-Yu
;
Liao, Chung-Hung
;
Lin, Man-Chun
Here, we report that long-term stable and efficient organic solar cells (OSCs) can be obtained through the following strategies: i) combination of rapid-drying blade-coating deposition with an appropriate thermal annealing treatment to obtain an optimized morphology of the active layer; ii) insertion of interfacial layers to optimize the interfacial properties. The resulting devices based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-2-carboxylate-2,6-diyl)] (PBDTTT-EFT):[6,6]-phenyl C-71 butyric acid methyl ester (PC71BM) blend as the active layer exhibits a power conversion efficiency (PCE) up to 9.57 %, which represents the highest efficiency ever reported for blade-coated OSCs. Importantly, the conventional structure devices based on poly(3-hexylthiophene) (P3HT):phenyl-C-61-butyric acid methyl ester (PCBM) blend can retain approximately 65% of their initial PCE for almost 2 years under operating conditions, which is the best result ever reported for long-term stable OSCs under operational conditions. More encouragingly, long-term stable large-area OSCs (active area = 216 cm(2)) based on P3HT:PCBM blend are also demonstrated. Our findings represent an important step toward the development of large-area OSCs with high performance and long-term stability.