• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.313-313
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• 2010

The performance of polymer photovoltaic cells based on blends of poly(3-hexylyhiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) is strongly influenced by blend composition and thickness. Polymer photovoltaic cells based on bulk-heterojunction have been fabricated with a structure of ITO/poly(3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)-pentacene/poly (3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM)/Al. We have prepared PEDOT:PSS by dissolving pentacene in N-methylpyrrolidine (NMP) and mixing with PEDOT:PSS. Pentacene was added a maximum concentration of approximately 5.5mg to the PEDOT:PSS solution and sonicated for 10 min. Active layer (P3HT:PCBM) (1:1) was strongly influenced by PEDOT:PSS-pentacene. We have investigated the performance of photovoltaic device with different concentration of P3HT:PCBM (1:1) 2.0wt%, 2.2wt%, 2.4wt% and 2.6wt%, respectively. The photocurrent and power conversion efficiency (PCE) showed a maximum between 2.0wt% and 2.2wt% concentration of P3HT:PCBM. This implied that both morphology and electron transport properties of the layer influenced the performance of the present photovoltaic cells. As the concentration of P3HT:PCBM blends as an active layer was increased, the power conversion efficiency was decreased. P3HT:PCBM layer and PEDOT:PSS-pentacene layer were characterized by work function, UV-visible absorption, atomic force microscopy (AFM), X-ray diffraction (XRD) and scanning electron microscope (SEM).

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.61.2-61.2
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• 2015

In the past decades, green energy, such as solar energy, wind power, hydropower, biomass energy, geothermal energy, and so on, has been widely investigated and developed to solve energy shortage. Recently, organic solar cells have attracted much attention, because they have many advantages, including low-cost, flexibility, light weight, and easy fabrication [1-3]. Organic solar cells are as a potential candidate of the next generation solar cells. In this abstract, to improve the power conversion efficiency and the stability, the inverted polymer solar cells with various structures were developed [4-6]. The novel cell structures included the P3HT:PCBM inverted polymer solar cells with AZO nanorods array, with pentacene-doped active layer, and with extra P3HT interfacial layer and PCBM interfacial layer. These three difference structures could respectively improve the performance of the P3HT:PCBM inverted polymer solar cells. For the inverted polymer solar cells with AZO nanorods array as the electronic transportation layer, by using the nanorod structure, the improvement of carrier collection and carrier extraction capabilities could be expected due to an increase in contact area between the nanorod array and the active layer. For the inverted polymer solar cells with pentacene-doped active layer, the hole-electron mobility in the active layer could be balanced by doping pentacene contents. The active layer with the balanced hole-electron mobility could reduce the carrier recombination in the active layers to enhance the photocurrent of the resulting inverted polymer solar cells. For the inverted polymer solar cells with extra P3HT and PCBM interfacial layers, the extra PCBM and P3HT interfacial layers could respectively improve the electron transport and hole transport. The extra PCBM interfacial layer served another function was that led more P3HT moving to the top side of the absorption layer, which reduced the non-continuous pathways of P3HT. It indicated that the recombination centers could be further reduced in the absorption layer. The extra P3HT interfacial layer could let the hole be more easily transported to the MoO3 hole transport layer. The high performance of the novel P3HT:PCBM inverted polymer solar cells with various structures were obtained.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.2
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• pp.63-67
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• 2010

The organic solar cells with Glass/ITO/PEDOT:PSS/P3HT:PCBM/Al structure were fabricated using regioregular poly (3-hexylthiophene) (P3HT) polymer:(6,6)- phenyl $C_{61}$-butyric acid methyl ester (PCBM) fullerene polymer as the bulk hetero-junction layer. The P3HT and PCBM as the electron donor and acceptor materials were spin casted on the indium tin oxide (ITO) coated glass substrates. The optimum mixing concentration ratio of photovoltaic layer was found to be P3HT:PCBM = 4:4 in wt%, indicating that the short circuit current density ($J_{SC}$), open circuit voltage ($V_{OC}$), fill factor (FF) and power conversion efficiency (PCE) values were about 4.7 $mA/cm^2$, 0.48 V, 43.1% and 0.97%, respectively. To investigate the effects of the post annealing treatment, as prepared organic solar cells were post annealed at the treatment time range from 5min to 20min at $150^{\circ}C$. $J_{SC}$ and $V_{OC}$ increased with increasing the post annealing time from 5min to 15min, which may be originated from the improvement of the light absorption coefficient of P3HT and improved ohmic contact between photo voltaic layer and Al electrode. The maximum $J_{SC},\;V_{OC}$, FF and PCE values of organic solar cell, which was post annealed for 15min at $150^{\circ}C$, were found to be about 7.8 $mA/cm^2$, 0.55 V, 47% and 2.0%, respectively.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.150-153
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• 2005

반도체성 고분자인 poly(3-hexylthiophene) (P3HT)과 $C_{60}$ 유도체인 PCBM의 복합재를 이용하여 유기태양전지를 제작하였다. 열처리 온도론 중심으로 다양한 제조조건 하에서의 태양전지 특성을 조사하였다. 열처리 온도를 높임에 따라, P3HT/PCBM 복합재 박막은 뚜렷한 색변화와 함께 가시광 영역에서의 광흡수가 증가됨이 관찰되었고, 소자 성능도 크게 향상되었다. 결과적으로, 본 P3HT/PCBM bulk 이종접합형 구조의 유기 태양전지는 최적화된 제조 조건에서 $2.8\%$의 에너지 전환 효율을 나타내었다($100mW/cm^2$, 백색광).

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.246-249
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• 2007

현재까지 $P3HT:C_{60}-PCBM$계는 고분자 유기 태양전지에서 가장 좋은 효율을 보여주고 있다. 그러나 보다 고효율의 소자 제작을 위해 신재료에 대한 연구들이 활발히 진행되고 있으며, 본 연구에서는 $C_{60}-PCBM$ 대신 $C_{70}-PCBM$을 합성하여 소자를 제작하였다. $C_{70}-PCBM$은 $C_{60}-PCBM$에 비하여 가시광선 영역에서 상대적으로 높은 광흡수율을 보여 주었으며, 이것은 광전류의 향상을 가져왔다. 소자제작의 주요 변수로 $P3HT:C_{70}-PCBM$ 광활성층의 처리 조건, 즉, 용매, 조성비, 열처리 조건, 광활성층의 두께 등을 조절하였는데, buffer층(LiF 층) 등이 도입되지 않은 간단한 제작조건 하에서도 본 $C_{70}-PCBM$는 $C_{60}-PCBM$계에 버금가는 3.5% (AM 1.5G, 100 $mW/cm^{2}$ 조건) 이상의 효율을 나타내었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.460-461
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• 2009

We studied the effects of post-annealing treatment on poly(3-hexylthiophene)(P3HT, donor):[6,6]-phenyl $C_{61}$ butyric acid methyl ester(PCBM, acceptor) blend film as an active layer in the organic solar cells(OSCs). For the formation of the active layer, 3 wt.% P3HT:PCBM solution in chlorobenzene were deposited by spin-coating method. In order to optimize the performance of OSCs, the P3HT crystallization and the redistribution of PCBM cluster at P3HT:PCBM composition as a function of post-annealing condition from room temperature to $200^{\circ}C$ were measured by the Hall effect and the UV-vis Spectrophotometer. We thought that the improved efficiency in the OSCs with post-annealing treatment at $150^{\circ}C$ can be explained by the efficient separation or collection of the photogenerated excitons at donor-acceptor interface by P3HT crystallization.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.1
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• pp.81-85
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• 2015

The organic/inorganic hybrid photovoltaic devices have been studied using Poly(3-hexylthiophene-2,5-diyl) (P3HT) : [6, 6]-Phenyl C61 butyric acid methyl ester (PCBM) and GaN. We traced the effect of short circuit current density with different annealing method under the various concentration and ratio of P3HT:PCBM. During the pre-annealing course, the heat treatments were performed each time at low temperature after the organic layer coated and the samples were heated at high temperature through one or two steps under the post-annealing process. It revealed that the samples with post-annealing process had higher values of short circuit current density than the other samples upon pre-annealing. And the interesting high short circuit current density features were observed at 1:1 mixing ratio and 1wt% of P3HT:PCBM.

• Textile Coloration and Finishing
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• v.26 no.4
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• pp.347-352
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• 2014

Film thickness dependent nanostructure evolution by a post annealing was investigated in poly (3-hexylthiophene):phenyl-C61-butyric acid methyl ester(P3HT:PCBM) films for organic solar cells which were fabricated by dichlorobenzene(DCB) solvent. In case of a 70nm thin film, the thermal annealing process affected to slight increment of the P3HT crystals in the surface region. On the other hand, large number of small sized P3HT crystals near the surface region was formed in the 200nm thick film. The solar cell devices showed the 3% power conversion efficiency(PCE) in 1:0.65 and 1:1 ratio(by weight) of P3HT and PCBM in 70nm and 200nm thickness conditions, respectively. Despite to the similar PCE, the short circuit current Jsc was different in 70nm and 200nm devices, which was related to the different nanostructure of P3HT:PCBM after thermal annealing.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.134-134
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• 2012

We investigated the interface of poly (3-hexylthiophene) (P3HT) and C61-butyric acid methylester (PCBM) by using photoelectron spectroscopy (PES). These are the most widely used materials for bulk heterojunction (BHJ) organic solar cells due to their high efficiency. Study of the BHJ interfaces is difficult because the organic films are typically prepared by spin coating in ambient conditions. This is incompatible with the interface electronic structure probes such as PES, which requires ultrahigh vacuum conditions. Study of interface requires gradual deposition of thin films that is also incompatible with the spin coating process. In this work, we used electrospray vacuum deposition (EVD) technique to deposit P3HT and PCBM in high vacuum conditions. EVD allows us to form polymer thin films onto ITO substrate in a step-wise manner directly from solutions and to use PES without exposing the sample to the ambient condition. Although the morphology of the EVD deposited P3HT films observed by optical and atomic force microscopes is quite different from that of the spin coated ones, the valence region spectra were similar. PCBM was deposited on the P3HT film in a similar manner and the energy level alignment between these two materials was studied. We discuss the relation between Voc of P3HT:PCBM solar cell and HOMO-LUMO energy offset obtained in this study.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.235-235
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• 2012

We investigated the energy levels of valence region at the planar junction of poly (3-hexylthiophene) (P3HT) and C61-butyric acid methylester (PCBM) using ultraviolet photoemission spectroscopy (UPS) with ultra high vacuum. These are the most widely used materials for bulk heterojunction (BHJ) organic solar cells due to their high efficiency. In order to make the planar junction, we carried out the electrospray vacuum deposition (EVD) of PCBM onto spin-coated P3HT in high vacuum conditions (${\sim}10^{-5}-10^{-6}$). The planar junction interface exhibited 0.71 eV for the offset between P3HT HOMO and PCBM LUMO, which is different from the gap (0.85 eV) of individual values and is closer to the open circuit voltage of solar cells fabricated with the same material combination.