We improve the performance of organic light-emitting diodes (OLEDs) with both a MoO3 hole injection layer (HIL) and a MoO3 doped hole transport layer (HTL), and present a systematical and comparative investigati...We improve the performance of organic light-emitting diodes (OLEDs) with both a MoO3 hole injection layer (HIL) and a MoO3 doped hole transport layer (HTL), and present a systematical and comparative investigation on these devices. Compared with OLEDs with only MoO3 HIL or MoO3 doped HTL, OLEDs with both MoO3 HIL and MoO3 doped HTL show superior performance in driving voltage, power efficiency, and stability. Based on the typical NPB/Alq3 heterojunction structure, OLEDs with both MoO3 HIL and MoO3 doped HTL show a driving voltage of 5.4 V and a power efficiency of 1.41 lm/W for 1000 cd/m2, and a lifetime of around 0. 88 h with an initial luminance of 5268 cd/m2 under a constant current of 190 mA/cm2 operation in air without encapsulation. While OLEDs with only MoO3 HIL or MoO3 doped HTL show higher driving voltages of 6.4 V or 5.8 V and lower power efficiencies of 1.201m/W or 1.341m/W for 1000cd/m2, and a shorter lifetime of 0.33 or 0.60h with an initial luminance of around 5122 or 5300cd/m2 under a constant current of 200 or 216mA/cm2 operation. Our results demonstrate clearly that using both MoO3 HIL and MoO3 doped HTL is a simple and effective approach to simultaneoasly improve both the hole injection and transport efficiency, resulting from the lowered energy barrier at the anode interface and the increased hole carrier density in MoO3 doped HTL.展开更多
We report an MoO3/Ag/Al/ZnO intermediate layer connecting two identical bulk heterojunction subcells with a poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT and PCBM) active layer for in...We report an MoO3/Ag/Al/ZnO intermediate layer connecting two identical bulk heterojunction subcells with a poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT and PCBM) active layer for inverted tan- dem polymer solar cells. The highly transparent intermediate layer with an optimized thickness realizes an Ohmic contact between the two subcells for effective charge extraction and recombination. A maximum power conversion efficiency of 3.76% is obtained for the tandem cell under 100 mW/cm2 illumination, which is larger than that of a single cell (3.15%). The open-circuit voltage of the tandem cell (1.18 V) approaches double that of the single cell (0.61 V).展开更多
Field enhancement and field screening are two major factors affecting field emission performance of arrays of quasi one-dimensional nanostruetures. We have observed enhanced field emission from large-area arrays of W1...Field enhancement and field screening are two major factors affecting field emission performance of arrays of quasi one-dimensional nanostruetures. We have observed enhanced field emission from large-area arrays of W18O49 pencil-like nanostructure due to both the effects of high aspect ratio and enlarged spacing between neighboring nanostructures. These arrays may be grown on silicon substrates by the multi-step thermal evaporation process. The spacing of nanotip-to-nanotip between neighboring nanostruetures may be increased by adjusting the growth temperature. The arrays are observed to have a typical turn-on field as low as about 1.26 MV/m and a threshold field as low as about 3.39 MV/m, resulting in increasing field enhancement and decreasing field screening effect.展开更多
We introduce a thin LiF layer into tris-8-hydroxyquinoline aluminium (Alq3 ) based bilayer organic light-emitting devices to block hole transport. By varying the thickness and position of this LiF layer in Alq3, we ...We introduce a thin LiF layer into tris-8-hydroxyquinoline aluminium (Alq3 ) based bilayer organic light-emitting devices to block hole transport. By varying the thickness and position of this LiF layer in Alq3, we obtain an electroluminescent efficiency increase by a factor of two with respect to the control devices without a LiF blocking layer. By using a 10nm dye doped Alq3 sensor layer, we prove that LiF can block holes and excitons effectively. Experimental results suggest that the thin LiF layer may be a good hole and exciton blocking layer.展开更多
InP solar cell is promising for space application due to its strong space radiation resistance and high power conversion efficient(PCE).Graphene/InP heterostructure solar cell is expected to have a higher PCE because ...InP solar cell is promising for space application due to its strong space radiation resistance and high power conversion efficient(PCE).Graphene/InP heterostructure solar cell is expected to have a higher PCE because strong near-infrared light can also be absorbed and converted additionally by graphene in this heterostructure.However,a low PCE was reported experimentally for Graphene/InP heterostructures.In this paper,electronic properties of graphene/InP heterostructures are calculated using density functional theory to understand the origin of the low PCE and propose possible improving ways.Our calculation results reveal that graphene contact with InP form a p-type Schottky heterostructure with a low Schottky barrier height(SBH).It is the low SBH that leads to the low PCE of graphene/InP heterostructure solar cells.A new heterostructure,graphene/insulating layer/InP solar cells,is proposed to raise SBH and PCE.Moreover,we also find that the opened bandgap of graphene and SBH in graphene/InP heterostructures can be tuned by exerting an electric field,which is useful for photodetector of graphene/InP heterostructures.展开更多
A new improved structure of dye- sensi- tized nanocrystalline solar cells (DSSC) for utilizing reflected light was introduced in this paper. Typical DSSC is based on a sandwich structure, which con- sists of photoanod...A new improved structure of dye- sensi- tized nanocrystalline solar cells (DSSC) for utilizing reflected light was introduced in this paper. Typical DSSC is based on a sandwich structure, which con- sists of photoanode, electrolyte and cathode. For the improved structure of DSSC in this paper, a sliver reflection film was attached to the back of transparent conducting glass of cathode. In this way, the residual light passing through photoanode was reflected to it to be used again. The photocurrent-voltage charac- teristics of DSSC fabricated by two different thickness of TiO2 film were measured to illustrate the effects of utilizing reflected light. As a result, the improved DSSC with reflection film exhibited higher photocur- rent and solar-to-electric conversion efficiency than DSSC without reflection film.展开更多
A novel solar cell fabricated with spiral photo-electrode for capturing sunlight 3-dimensionally (3D-cell) is proposed in this paper. We studied its performance both in solar simulator and in nature sunlight. Spiral p...A novel solar cell fabricated with spiral photo-electrode for capturing sunlight 3-dimensionally (3D-cell) is proposed in this paper. We studied its performance both in solar simulator and in nature sunlight. Spiral photo-electrode of 3D-cell can receive sunlight from all directions and therefore can track the sun passively. And it is much insensitive to solar azimuth angle and shade. In addition, it increases the area to obtain scattered sunlight and reflected light. Compared with the dye-sensitized solar cells using sandwich structure, it would be more advantageous in the sealing technique.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No 11274402the National Basic Research Program of China under Grant No 2012CB933704+1 种基金the Natural Science Foundation of Guangdong Province under Grant No S2012020011003the Program for Changjiang Scholars and Innovative Research Team in University under Grant No IRT13042
文摘We improve the performance of organic light-emitting diodes (OLEDs) with both a MoO3 hole injection layer (HIL) and a MoO3 doped hole transport layer (HTL), and present a systematical and comparative investigation on these devices. Compared with OLEDs with only MoO3 HIL or MoO3 doped HTL, OLEDs with both MoO3 HIL and MoO3 doped HTL show superior performance in driving voltage, power efficiency, and stability. Based on the typical NPB/Alq3 heterojunction structure, OLEDs with both MoO3 HIL and MoO3 doped HTL show a driving voltage of 5.4 V and a power efficiency of 1.41 lm/W for 1000 cd/m2, and a lifetime of around 0. 88 h with an initial luminance of 5268 cd/m2 under a constant current of 190 mA/cm2 operation in air without encapsulation. While OLEDs with only MoO3 HIL or MoO3 doped HTL show higher driving voltages of 6.4 V or 5.8 V and lower power efficiencies of 1.201m/W or 1.341m/W for 1000cd/m2, and a shorter lifetime of 0.33 or 0.60h with an initial luminance of around 5122 or 5300cd/m2 under a constant current of 200 or 216mA/cm2 operation. Our results demonstrate clearly that using both MoO3 HIL and MoO3 doped HTL is a simple and effective approach to simultaneoasly improve both the hole injection and transport efficiency, resulting from the lowered energy barrier at the anode interface and the increased hole carrier density in MoO3 doped HTL.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB933704)the Doctoral Foundation of the Ministry of Education of China(Grant No.20100171110025)the State Key Laboratory of Optoelectronic Materials and Technologies,Sun Yat-Sen University,China(GrantNo.2010-RC-3-1)
文摘We report an MoO3/Ag/Al/ZnO intermediate layer connecting two identical bulk heterojunction subcells with a poly(3-hexylthiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT and PCBM) active layer for inverted tan- dem polymer solar cells. The highly transparent intermediate layer with an optimized thickness realizes an Ohmic contact between the two subcells for effective charge extraction and recombination. A maximum power conversion efficiency of 3.76% is obtained for the tandem cell under 100 mW/cm2 illumination, which is larger than that of a single cell (3.15%). The open-circuit voltage of the tandem cell (1.18 V) approaches double that of the single cell (0.61 V).
基金Supported by the National Natural Science Foundation of China under Grant Nos 50725206,50802117,U0634002 and 50672135the National Basic Research Program of China under Grant Nos 2003CB314701,2007CB935501 and 2010CB327703+4 种基金the National High-Tech Research and Development Program of China under Grant No2008AA03A314the Doctoral Foundation of Education Ministry of China under Grant No 20070558063the Science and Technology Department of Guangdong Provincethe Department of Information Industry of Guangdong Provincethe Science and Technology Department of Guangzhou City.
文摘Field enhancement and field screening are two major factors affecting field emission performance of arrays of quasi one-dimensional nanostruetures. We have observed enhanced field emission from large-area arrays of W18O49 pencil-like nanostructure due to both the effects of high aspect ratio and enlarged spacing between neighboring nanostructures. These arrays may be grown on silicon substrates by the multi-step thermal evaporation process. The spacing of nanotip-to-nanotip between neighboring nanostruetures may be increased by adjusting the growth temperature. The arrays are observed to have a typical turn-on field as low as about 1.26 MV/m and a threshold field as low as about 3.39 MV/m, resulting in increasing field enhancement and decreasing field screening effect.
基金Supported by the National Natural Science Foundation of China under Grant No 10504044, and the Fok Ying Tung Education Foundation under Grant No 101007.
文摘We introduce a thin LiF layer into tris-8-hydroxyquinoline aluminium (Alq3 ) based bilayer organic light-emitting devices to block hole transport. By varying the thickness and position of this LiF layer in Alq3, we obtain an electroluminescent efficiency increase by a factor of two with respect to the control devices without a LiF blocking layer. By using a 10nm dye doped Alq3 sensor layer, we prove that LiF can block holes and excitons effectively. Experimental results suggest that the thin LiF layer may be a good hole and exciton blocking layer.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.12074441,11774438,and 12104518)Guangdong Basic and Applied Basic Foundation in China(Grant No.2019A1515011572 and 2022A1515012643).
文摘InP solar cell is promising for space application due to its strong space radiation resistance and high power conversion efficient(PCE).Graphene/InP heterostructure solar cell is expected to have a higher PCE because strong near-infrared light can also be absorbed and converted additionally by graphene in this heterostructure.However,a low PCE was reported experimentally for Graphene/InP heterostructures.In this paper,electronic properties of graphene/InP heterostructures are calculated using density functional theory to understand the origin of the low PCE and propose possible improving ways.Our calculation results reveal that graphene contact with InP form a p-type Schottky heterostructure with a low Schottky barrier height(SBH).It is the low SBH that leads to the low PCE of graphene/InP heterostructure solar cells.A new heterostructure,graphene/insulating layer/InP solar cells,is proposed to raise SBH and PCE.Moreover,we also find that the opened bandgap of graphene and SBH in graphene/InP heterostructures can be tuned by exerting an electric field,which is useful for photodetector of graphene/InP heterostructures.
文摘A new improved structure of dye- sensi- tized nanocrystalline solar cells (DSSC) for utilizing reflected light was introduced in this paper. Typical DSSC is based on a sandwich structure, which con- sists of photoanode, electrolyte and cathode. For the improved structure of DSSC in this paper, a sliver reflection film was attached to the back of transparent conducting glass of cathode. In this way, the residual light passing through photoanode was reflected to it to be used again. The photocurrent-voltage charac- teristics of DSSC fabricated by two different thickness of TiO2 film were measured to illustrate the effects of utilizing reflected light. As a result, the improved DSSC with reflection film exhibited higher photocur- rent and solar-to-electric conversion efficiency than DSSC without reflection film.
文摘A novel solar cell fabricated with spiral photo-electrode for capturing sunlight 3-dimensionally (3D-cell) is proposed in this paper. We studied its performance both in solar simulator and in nature sunlight. Spiral photo-electrode of 3D-cell can receive sunlight from all directions and therefore can track the sun passively. And it is much insensitive to solar azimuth angle and shade. In addition, it increases the area to obtain scattered sunlight and reflected light. Compared with the dye-sensitized solar cells using sandwich structure, it would be more advantageous in the sealing technique.