Inorganic–Organic Hybrid Solar Cell: Bridging Quantum Dots to Conjugated Polymer Nanowires (original) (raw)
Related papers
Electrochimica Acta, 2016
In this work, CdSe nanocrystals crosslinking by m-phenylenediamine (MPD) was used as an effective method for improving charge transport and enhancing the performance of CdSe/Poly(3-Hexylthiophene) (P3HT) hybrid solar cell. Fourier transform infrared (FTIR) spectra were used to illustrate the crosslinking process by diamine treatment. Binding of MPD molecules to the nanocrystals surface and replacement of initial ligands (pyridine and oleic acid) during MPD treatment were detected by FTIR. The result of nanocrystals treatment with MPD was a 30% power conversion efficiency (PCE) improvement by enhancement of short circuit current density (J sc) from 5.4 to 6 mA/cm 2 , open circuit voltage (V oc) from 0.7 to 0.76 V, and fill factor (FF) from 0.4 to 0.43. The J sc improvement was attributed to the nanocrystals bridging and charge transport enhancement. Besides, the recombination reduction and charge lifetime enhancement after MPD treatment were the reasons of V oc increase. AFM images showed that the morphology of hybrid active layer did not change noticeably with MPD treatment. Quantum dots (QDs) crosslinking maked the hybrid film resistant to dissolution and flaking in solvents such as dichlorobenzene which provides the fabrication of multilayers. 2016 Elsevier Ltd. All rights reserved.
Next Generation (Nano) Photonic and Cell Technologies For Solar Energy Conversion Iii, 2012
Semiconductor quantum dots (QDs) are characterized by high extinction coefficients adjustable by varying the nanoparticle size and a high quantum yield of charge generation. They have the advantage of efficient charge transfer from QDs to organic semiconductors. An advanced photovoltaic cell where a SnO 2 /ITO electrode is covered with layers of CdSe QDs integrated in a polyimide (PI) organic semiconductor (about 100 nm thick) and Cu-phthalocyanine (20-40 nm thick) has been developed.
Solar Energy Materials and Solar Cells, 2011
We report on the efficiency enhancement for bulk-heterojunction hybrid solar cells based on hexanoic acid treated trioctylphosphine/oleic acid-capped CdSe quantum dots (QDs) and low bandgap polymer poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b 0 ]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) compared to devices based on poly(3-hexylthiophene) (P3HT). Photovoltaic devices with optimized polymer:QD weight ratio, photoactive film thickness, thermal annealing treatment, and cathode materials exhibited a power conversion efficiency of 2.7% after spectral mismatch correction, which is the highest reported value for spherical CdSe QD based photovoltaic devices. The efficiency enhancement is attributed to the surface treatment of the QDs together with the use of the low bandgap polymer PCPDTBT leading to an increased short-circuit current density due to additional light absorption between 650 and 850 nm. Our results suggest that the hexanoic acid treatment is generally applicable to various ligand-capped CdSe and confirm that low bandgap polymers with adequate HOMO and LUMO levels are promising to be incorporated into hybrid solar cells for further device performance improvement.
Macromolecules, 2009
The pending global energy crisis requires the development of new technologies that exploit the potential of renewable sources of energy, such as solar power. For example, inorganic semiconductor-based photovoltaic technology has reached the performance level of converting 30% solar energy into electric power. 1,2 Despite the high performance, inorganic photovoltaics based on crystalline silicon are still too expensive to compete with the conventional sources of electricity. While extensive research in the field of inorganic photovoltaics is expected to result in a decrease in their fabrication cost, polymer-based photovoltaics represent a very attractive alternative for low-cost, lightweight, large-area, and flexible solar panels. The most used conjugated polymers in photovoltaic structures are regioregular poly (3-alkylthiophenes) and alkoxy-substituted poly(phenylenevinylenes), such as poly[2-methoxy-5-(2 0 -ethylhexyloxy)-1,4-phenylenevinylene] and poly[2-methoxy-5-(3 0 ,7 0 -dimethyloctyloxy)-pphenylenevinylene]. 4 Because of their solubility in organic solvents, these polymers are suitable for casting from solution using wet-processing techniques, such as spin-casting, dip-coating, ink jet printing, screen printing, and micromolding. 4 Blending of two materials having donor and acceptor properties results in the formation of a bulk heterojunction. 4 Research has been directed toward four important types of bulk heterojunctions. The first type consists of a polymer-polymer heterojunction obtained by mixing of two conjugated polymers with offset energy levels. The second type is obtained by blending a conjugated polymer with (6,6)-phenyl-C 61 -butyric acid methyl ester (PCBM) as a soluble electron acceptor, which currently shows the best performance. 2,6 Polymer/titania (TiO 2 ) photovoltaic cell represents the third type of bulk heterojunction, which has received attention due to the possibility of TiO 2 patterning into a continuous network for electron transport. 7,8 Conjugated polymer quantum dots can be considered the fourth type of bulk heterojunction solar cells. For example, CdSe nanocrystals with an electron affinity in the range 3.8-4.5 eV are suitable materials to act as electron acceptors when combined with conjugated polymers. 9-12 The band gap for quantum dots is controlled simply by adjusting the size of the dots. Semiconductor quantum dots (QDs) have attracted enormous interest in the past two decades due to their tunable optical and electronic properties. Remarkable efforts have been devoted to the synthesis of high-quality, defect-free QDs with narrow size distribution (<5%). 13 These interesting properties of QDs have been employed for various applications including biosensing, light-emitting diodes, and photovoltaics. Poly(3-alkylthiophenes) are one the most attractive candidates for photovoltaic applications due to their opto-electronic properties, stability, and solution processability. 18 Poly(3-hexylthiophene) (P3HT) has shown hole mobilities as high as 0.1 cm 2 V -1 s -1 and crystallinities as a function of the processing conditions. These are important parameters when considering photovoltaic applications where the effect of charge recombination should be minimized.
Advanced Theory and Simulations
The power conversion efficiency (PCE) of a hybrid bulk hetero-junction organic solar cell with an active layer of a blend of PBDT TS1 (donor) and PCBM (acceptor) incorporated with copper zinc tin sulfide (CZTS) quantum dots (QDs) and zinc oxide (ZnO) nanowires is simulated. It is found that the incorporation of CZTS-QDs of a single radius (1.5 nm) enhances the PCE from 9.1% to 12.34% and of 13 different radii CZTS-QDs elevates PCE to 14.96%. This enhancement occurs mainly due to the enhancement in absorption that enhances short-circuit current density (J sc) and fill factor (FF). Finally, a layer of ZnO nanowires is added on top of the glass to reduce the reflection losses and absorption of ultraviolet light in the active layer that causes degradation and reduces the stability of organic solar cells (OSCs). The hybrid structure, thus simulated, has an enhanced PCE of 16.32% and is expected to be relatively more stable. It is expected that the results of this simulation may inspire all researchers interested in the fabrication of highly efficient hybrid OSCs.
Molecular-level control of polymer/nanocrystal interface towards efficient hybrid solar cells
arXiv: Materials Science, 2013
Colloidal narrow bandgap semiconductor nanocrystals are regarded as attractive components in hybrid organic/inorganic composites for solution-processed photovoltaic applications. However, solar cells comprising polythiophene conjugated polymers and lead chalcogenide nanocrystals, which are among the most commonly used materials for photovoltaics, have been considered inefficient as a result of poor charge separation from the hybrid interface. Here we demonstrate that tailoring the nanocrystal surface chemistry drastically impacts the morphology and optoelectronic properties of composites based on poly(3-hexylthiophene) and lead sulfide nanocrystals, promoting long-lived charge separation and enabling the fabrication of bulk-heterojunction solar cells which display an outstanding thousand-fold enhancement of the power conversion efficiency, reaching 3 %. We thus provide a simple yet powerful strategy to gain control over the optoelectronic properties of hybrid composites by tailoring...
Morphological consequences of ligand exchange in quantum dot - Polymer solar cells
Organic Electronics, 2018
Mixtures of conjugated polymers and quantum dot nanocrystals present an interesting solution-processable materials system for active layers in optoelectronic devices, including solar cells. We use scanning transmission electron microscopy to investigate the effects of exchanging the capping ligand of quantum dots on the threedimensional morphology of the film. We created 3D reconstructions for blends of poly((4,8-bis(octyloxy)benzo (1,2-b:4,5-b')-dithiophene-2,6-diyl)(2-((dodecyloxy)carbonyl)thieno (3,4-b)-thiophenediyl)) (PTB1) and PbS quantum dots capped with oleic acid (OA), butylamine (BA), OA to 3-mercaptopropionic acid (MPA), and BA to MPA. We use these reconstructed volumes to evaluate differences in exciton dissociation and charge transport as a function of ligand processing. We show that the MPA exchange without an intermediate BA treatment results in severe changes to the film structure and a non-ideal morphology for an effective device. We also show that with a BA exchange, the morphology remains largely unchanged with the additional MPA treatment. This quantitative characterization elucidates previously reported device performance changes caused by ligand exchange and should inform future device fabrication protocols.
Ligand engineering in hybrid polymer:nanocrystal solar cells
Materials Today, 2015
Blends of semiconducting polymers and inorganic semiconductor nanocrystals are receiving renewed interest as a type of inexpensive, solution-processed third generation solar cell. In these hybrid bulk heterojunctions (BHJs), the interface between the disparate organic and inorganic phases is a dominating factor in the overall performance of the resulting devices. Paramount to this interface is the ligand landscape on the nanocrystal surface, which as a result of the inherently large surface area to volume ratio of the nanocrystals, has a significant spatial and electronic influence on the boundary between the donor polymer and acceptor nanocrystal. We have investigated the importance of this three-part polymer/ligand/nanocrystal interface by studying the ligand effects in hybrid BHJ solar cells. In this article, we highlight the major research advances and the state-of-the-art in hybrid BHJ solar cells with respect to ligand engineering, as well as outline future research avenues deemed necessary for continued technological advancement.
Heterojunction Photovoltaics Using GaAs Nanowires and Conjugated Polymers
Nano Letters, 2011
We demonstrate an organic/inorganic solar cell architecture based on a blend of poly(3-hexylthiophene) (P3HT) and narrow bandgap GaAs nanowires. The measured increase of device photocurrent with increased nanowire loading is correlated with structural ordering within the active layer that enhances charge transport. Coating the GaAs nanowires with TiO x shells passivates nanowire surface states and further improves the photovoltaic performance. We find that the P3HT/ nanowire cells yield power conversion efficiencies of 2.36% under white LED illumination for devices containing 50 wt % of TiO x-coated GaAs nanowires. Our results constitute important progress for the use of nanowires in large area solution processed hybrid photovoltaic cells and provide insight into the role of structural ordering in the device performance.
Applied Physics Letters, 2010
We report on bulk-heterojunction hybrid solar cells based on blends of non-ligand-exchanged CdSe quantum dots ͑QDs͒ and the conjugated polymer poly͑3-hexylthiophene͒ with improved power conversion efficiencies of about 2% under AM1.5G illumination after spectral mismatch correction. This is the highest reported value for a spherical CdSe QD based photovoltaic device. After synthesis, the CdSe QDs are treated by a simple and fast acid-assisted washing procedure, which has been identified as a crucial factor in enhancing the device performance. A simple model of a reduced ligand sphere is proposed explaining the power conversion efficiency improvement.