Temperature dependence of polymer/fullerene organic solar cells

Bagienski, Will; Gupta, Mool C.

doi:10.1016/j.solmat.2010.11.026

Cited by 37 publications

(21 citation statements)

References 26 publications

(50 reference statements)

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“…The temperature dependence studies of different I-V parameters of a small-molecular donor/acceptor system [copper phthalocyanine(CuPc)/fullerene(C 60 )] have been reported [9], [12]. The V oc of the CuPc/C 60 solar cell showed the same decreasing trend when the temperature increased as Bagienski and Gupta [8] found out in their study. The model for conventional inorganic semiconductor solar cells has been used to explain the decreasing trend of open-circuit voltage with temperature.…”

Section: Introductionmentioning

confidence: 63%

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Temperature Dependence of Open-Circuit Voltage and UPS Study for P3HT:PCBM Organic Solar Cells

Shen

Scudiero

Gupta

2012

IEEE J. Photovoltaics

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In this paper, the open-circuit voltage V o c of a poly(3-hexylthiophene-2,5-diyl) (P3HT) and a [6,6]-phenyl C 61 -butyric acid methyl ester (PCBM) bulk heterojunction organic solar cell device was measured at temperatures ranging from 15 • C to 145 • C. The temperature dependence of the vacuum shift and of the highest occupied molecular orbital (HOMO) energy level of P3HT and PCBM were measured by ultraviolet photoelectron spectroscopy in the same temperature range. The temperature dependence of the absorption edge was also studied in the same temperature range to obtain the temperature variation of the optical band gap energy E g . The measured V o c of the devices shows a clear decreasing trend with increasing operating temperature, and the total decrease is found to be about 0.1 V. However, by utilizing the measured values of the HOMO for the P3HT (donor) and of the determined lowest unoccupied molecular orbital (LUMO) for the PCBM (acceptor), we have found that the calculated values of V o c and its temperature dependence do not agree with the measured V o c values. This is a clear indication that the expression (HOMO-LUMO)-exciton energy does not hold and that other factors are impacting the value of V o c . Index Terms-Atomic force microscopy (AFM), highest occupied molecular orbital-lowest unoccupied molecular orbital (HUMO-LUMO), open-circuit voltage, organic solar cells, ultraviolet photoelectron spectroscopy (UPS).

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Section: Introductionmentioning

confidence: 63%

“…Recently, Bagienski and Gupta [8] reported detail results on the temperature dependence of absorption, fluorescence, and various solar cell parameters. In this study, P3HT and PCBM were chosen due to the great interest for the fabrication of BHJ) devices with their possible solar cell efficiency of 5% and lowcost fabrication [10], [11].…”

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Open-Circuit Voltage and UPS Study for P3HT:PCBM Organic Solar Cells

Shen

Scudiero

Gupta

2012

IEEE J. Photovoltaics

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“…13. It is observed that the degree of PL quenching decreases for the annealed films [48] (air and Ar atmospheres), as depicted in Fig. 13a, b.…”

Section: Photoluminescence Spectroscopymentioning

confidence: 72%

Comparative study: the effect of annealing conditions on the properties of P3HT:PCBM blends

et al. 2012

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This paper presents a detailed study on the role of various annealing treatments on organic poly(3-hexylthiophene) and [6]-phenyl-C 61 -butyric acid methyl ester blends under different experimental conditions. A combination of analytical tools is used to study the alteration of the phase separation, structure and photovoltaic properties of the P3HT:PCBM blend during the annealing process. Results showed that the thermal annealing yields PCBM ''needle-like'' crystals and that prolonged heat treatment leads to extensive phase separation, as demonstrated by the growth in the size and quantity of PCBM crystals. The substrate annealing method demonstrated an optimal morphology by eradicating and suppressing the formation of fullerene clusters across the film, resulting in longer P3HT fibrils with smaller diameter. Improved optical constants, PL quenching and a decrease in the P3HT optical bad-gap were demonstrated for the substrate annealed films due to the limited diffusion of the PCBM molecules. An effective strategy for determining an optimized morphology through substrate annealing treatment is therefore revealed for improved device efficiency. IntroductionOrganic photovoltaic (OPV) solar cells have attracted significant attention due to their great potential for large-area, light-weight, flexible, and low-cost devices [1][2][3][4]. Recently, OPV research has been dominated by the poly(3-hexylthiophene):[6]-phenyl C 61 -butyric acid methyl ester (P3HT: PCBM) blend reaching power conversion efficiencies (PCEs) of 5-7 % [5,6]. Most recently a record PCE of about 8.13 and 8.5 % has been reported [7, 8]. Despite recent achievements, improvement in PCEs, stability and lifetime of the devices are necessary before organic solar cells become commercially viable [9][10][11]. The PCE of the solar cells based on the P3HT/fullerene system depends strongly on the processing conditions [12] and can be improved by increasing the crystalline content of the P3HT. Different approaches have been suggested for the optimization of the morphology, such as thermal annealing [5,6,[13][14][15]

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“…• C. The UPS measured HOMO and LUMO levels and the measured V OC [52] were compared. The exciton binding energy was also measured to further examine the reported empirical formulas.…”

Section: Statement Of the Problemmentioning

confidence: 99%

Investigation of Electrical Properties of P3HT:PCPBM Organic Solar Cells

Shen

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The electrical properties of organic solar cells (OSC) have been investigated to understand the charge loss mechanisms impacting the over all efficiency. The power conversion efficiency of a solar cell is dependent upon the short-circuit current density (J SC ), open circuit voltage (V OC ) and the fill factor (FF). This thesis is mainly about the investigation of these properties in two aspects: the current conducting mechanism is studied via electrical resistance measurements of the OSC devices and the origin of V OC is investigated through the fundamental studies using ultraviolet photoelectron spectroscopy (UPS).In the current conducting mechanism study, the series resistance of poly (3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl C61-butyric acid methyl ester (PCB-M) bulk heterojunction (BHJ) organic solar cells (OSC) has been investigated. The bulk resistance of the active layer and the specific contact resistance between the active layer and the electrode are extracted from the measured series resistance using the vertical transmission line model (TLM) method. Results have shown that for an annealed P3HT:PCBM device which has an active layer thickness of 85 nm (optimum thickness for high efficiency), 17% of the total series resistance is attributed to contact resistance and bulk resistance contributed the rest 83%. Thermal annealing helps to reduce the contact resistance by a factor of 2 and the bulk resistance by a factor of 8. The resistances of pure PCBM devices increase linearly with thickness, while the increasing trend of the pure P3HT devices can be described as two different increasing regions, mainly due to the recombination effect.The origin of V OC is investigated through UPS study. V OC of P3HT and PCBM organic solar cell devices is measured at temperatures ranging from 15• C to 145

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Temperature dependence of polymer/fullerene organic solar cells

Cited by 37 publications

References 26 publications

Temperature Dependence of Open-Circuit Voltage and UPS Study for P3HT:PCBM Organic Solar Cells

Temperature Dependence of Open-Circuit Voltage and UPS Study for P3HT:PCBM Organic Solar Cells

Comparative study: the effect of annealing conditions on the properties of P3HT:PCBM blends

Investigation of Electrical Properties of P3HT:PCPBM Organic Solar Cells

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