Temperature dependent characteristics of poly(3 hexylthiophene)-fullerene based heterojunction organic solar cells

Abstract

Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Electrical and optical properties of poly͑3-hexylthiophene-2.5diyl͒ ͑P3HT͒ used as the main component in a polymer/fullerene solar cell were studied. From the study of space-charge limited current behavior of indium-tin-oxide ͑ITO͒/P3HT/Au hole-only devices, the hole mobility and density were estimated to range from 1.4ϫ10 Ϫ6 cm 2 /V s and 5.3ϫ10 14 cm Ϫ3 at 150 K to 8.5 ϫ10 Ϫ5 cm 2 /V s and 1.1ϫ10 15 cm Ϫ3 at 250 K, respectively. The highest occupied to lowest occupied molecular orbital energetic difference was estimated from absorption spectrometry to be about 2.14 eV. Strong quenching of photoluminescence when the polymer was mixed with ͓6,6͔-phenyl-C 61 butyric acid methyl ester ͑PCBM͒, provided evidence of photoinduced charge transfer from P3HT to PCBM. Characterization of ITO/PEDOT:PSS/P3HT:PCBM/Al solar cells was done by analyzing the dependence of current density-voltage characteristics on temperature and illumination intensity. The main solar cell characteristics recorded at 300 K under 100 mW/cm 2 white-light intensity were: Open-circuit voltage 0.48 V, current density 1.28 mA/cm 2 , with an efficiency of 0.2%, and fill factor of 30.6%. Open-circuit voltage decreased almost linearly with increasing temperature, while short circuit current density increased with temperature, saturating at around 320 K, and decreased thereafter. Power conversion efficiency and fill factor were maximum around 3 mW/cm 2 due to the poor bulk transport properties of the active layer.

Field-dependent exciton dissociation in organic heterojunction solar cells

“…36 An increase of the cell temperature from 9 • C to 48 • C decreased V oc by about 9% from 1.11 to 1.01 V and increased J sc by about 7% from 5.81mA cm −2 to 6.21mA cm −2 . The obtained temperature coefficient dV oc /dT ≈ −2.6 mV K −1 for the material system ID583/C 60 was larger than values for other organic D/A systems [37][38][39] and comparable to the values found in past generations of silicon pn-junction solar cells. 40 In contrast to the pronounced influence of the cell thickness, the cell temperature had nearly no influence on the approximately linear photocurrent-voltage response in the voltage range between 0.3 and 0.9 V.…”

Control of the electrode work function and active layer morphology via surface modification of indium tin oxide for high efficiency organic photovoltaics

“…In bulk heterojunction solar cells using poly͑3-hexylthiophene͒ doped ͓6:6͔-phenyl-C61 butyric acid methyl ester ͑P3HT:PCBM͒, morphology control of active layer is very important. Additionally, through thermal annealing of P3HT:PCBM blend devices, the external quantum efficiency and power conversion efficiency of these cells are dramatically increased; 16 In these cases, a power conversion efficiency for a P3HT/PCBM blend system as high as about 3% has been reported. 17 Many studies have shown that poor morphology, i.e., the severe phase separation of the active layer, is a key factor in loss of device performance.…”

Light intensity dependence of open-circuit voltage of polymer:fullerene solar cells

“…͑2͒ has also been applied to explain the temperature dependence of V oc of polymer:fullerene bulk heterojunction solar cells. 5,6 However, it is not clear whether such an analysis in terms of an ideal solar cell is justified for the case of polymer:fullerene bulk heterojunctions. Moreover, the fact that both J sc and J s are also temperature dependent further complicates the applicability of Eq.…”

“…Equation ͑6͒ can be rewritten in terms of the quasi-Fermi levels as 6 TABLE I. Overview of ideality factors n obtained from …”