scholarly journals Solution-processed, semitransparent organic photovoltaics integrated with solution-doped graphene electrodes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jan-Kai Chang ◽  
Yu-Yun Huang ◽  
Ding-Lun Lin ◽  
Jieh-I. Tau ◽  
Ting-Hao Chen ◽  
...  
Keyword(s):  
Organic Photovoltaics ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Solution Processed ◽  
Doped Graphene ◽  
Control Devices ◽  
Visible Wavelengths ◽  
Transfer Method ◽  
Good Transparency ◽  
Solution Doping

AbstractIn this work, by applying a transfer method simultaneously with a solution doping process for graphene as top electrodes, we demonstrate a solution-processed semitransparent organic photovoltaics (OPV). The work function of doped graphene under various doping conditions was investigated via photoemission spectroscopy. The transparent device was fabricated using PEDOT-doped graphene as electrodes, which provide an energetically favorable band alignment for carrier extractions. The solution-processed semitransparent organic photovoltaics exhibit the power conversion efficiency (PCE) of 4.2%, which is 85.7% of the PCE of control devices based on metallic reflecting electrodes, while maintaining good transparency at most visible wavelengths.

scholarly journals Ultrafast Charge Separation in Bilayer WS2/Graphene Heterostructure Revealed by Time- and Angle-Resolved Photoemission Spectroscopy

2021 ◽  
Vol 9 ◽  
Author(s):  
Razvan Krause ◽  
Mariana Chávez-Cervantes ◽  
Sven Aeschlimann ◽  
Stiven Forti ◽  
Filippo Fabbri ◽  
...  
Keyword(s):  
Charge Separation ◽  
Graphene Layer ◽  
Optoelectronic Devices ◽  
Visible Spectral Range ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Type I ◽  
Type Ii ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Indirect Band Gap

Efficient light harvesting devices need to combine strong absorption in the visible spectral range with efficient ultrafast charge separation. These features commonly occur in novel ultimately thin van der Waals heterostructures with type II band alignment. Recently, ultrafast charge separation was also observed in monolayer WS2/graphene heterostructures with type I band alignment. Here we use time- and angle-resolved photoemission spectroscopy to show that ultrafast charge separation also occurs at the interface between bilayer WS2 and graphene indicating that the indirect band gap of bilayer WS2 does not affect the charge transfer to the graphene layer. The microscopic insights gained in the present study will turn out to be useful for the design of novel optoelectronic devices.

A New Fullerene-Free Bulk-Heterojunction System for Efficient High-Voltage and High-Fill Factor Solution-Processed Organic Photovoltaics

2015 ◽  
Vol 27 (11) ◽  
pp. 1900-1907 ◽  
Author(s):  
Zheng Tang ◽  
Bo Liu ◽  
Armantas Melianas ◽  
Jonas Bergqvist ◽  
Wolfgang Tress ◽  
...  
Keyword(s):  
High Voltage ◽  
Organic Photovoltaics ◽  
Fill Factor ◽  
Bulk Heterojunction ◽  
Factor Solution ◽  
Solution Processed ◽  
High Fill Factor

Study of Band Alignment at CBD-CdS/Cu(In1-xGax)Se2 (x = 0.2 - 1.0) Interfaces by Photoemission and Inverse Photoemission Spectroscopy

2007 ◽  
Vol 1012 ◽  
Author(s):  
Shimpei Teshima ◽  
Hirotake Kashiwabara ◽  
Keimei Masamoto ◽  
Kazuya Kikunaga ◽  
Kazunori Takeshita ◽  
...  
Keyword(s):  
Band Gap ◽  
Conduction Band ◽  
Valence Band Maximum ◽  
Band Gap Energy ◽  
Band Alignment ◽  
Photoemission Spectroscopy ◽  
Gap Energy ◽  
Conduction Band Offset ◽  
Inverse Photoemission ◽  
Inverse Photoemission Spectroscopy

AbstractDependence of band alignments at interfaces between CdS by chemical bath deposition and Cu(In1-xGax)Se2 by conventional 3-stage co-evaporation on Ga substitution ratio x from 0.2 to 1.0 has been systematically studied by means of photoemission spectroscopy (PES) and inverse photoemission spectroscopy (IPES). For the specimens of the In-rich CIGS, conduction band minimum (CBM) by CIGS was lower than that of CdS. Conduction band offset of them was positive about +0.3 ~ +0.4 eV. Almost flat conduction band alignment was realized at x = 0.4 ~ 0.5. On the other hand, at the interfaces over the Ga-rich CIGS, CBM of CIGS was higher than that of CdS, and CBO became negative. The present study reveals that the decrease of CBO with a rise of x presents over the wide rage of x, which results in the sign change of CBO around 0.4 ~ 0.45. In the Ga-rich interfaces, the minimum of band gap energy, which corresponded to energy spacing between CBM of CdS and valence band maximum of CIGS, was almost identical against the change of band gap energy of CIGS. Additionally, local accumulation of oxygen related impurities was observed at the Ga-rich samples, which might cause the local rise of band edges in central region of the interface.

scholarly journals High-performance, semiconducting membrane composed of ultrathin, single-crystal organic semiconductors

2019 ◽  
Vol 117 (1) ◽  
pp. 80-85 ◽  
Author(s):  
Tatsuyuki Makita ◽  
Shohei Kumagai ◽  
Akihito Kumamoto ◽  
Masato Mitani ◽  
Junto Tsurumi ◽  
...  
Keyword(s):  
Single Crystal ◽  
Organic Semiconductors ◽  
High Performance ◽  
Printed Electronics ◽  
Electronic Device ◽  
Molecular Layer ◽  
High Mobility ◽  
Building Blocks ◽  
Solution Processed ◽  
Transfer Method

Thin film transistors (TFTs) are indispensable building blocks in any electronic device and play vital roles in switching, processing, and transmitting electronic information. TFT fabrication processes inherently require the sequential deposition of metal, semiconductor, and dielectric layers and so on, which makes it difficult to achieve reliable production of highly integrated devices. The integration issues are more apparent in organic TFTs (OTFTs), particularly for solution-processed organic semiconductors due to limits on which underlayers are compatible with the printing technologies. We demonstrate a ground-breaking methodology to integrate an active, semiconducting layer of OTFTs. In this method, a solution-processed, semiconducting membrane composed of few-molecular-layer–thick single-crystal organic semiconductors is exfoliated by water as a self-standing ultrathin membrane on the water surface and then transferred directly to any given underlayer. The ultrathin, semiconducting membrane preserves its original single crystallinity, resulting in excellent electronic properties with a high mobility up to 12cm2⋅V−1⋅s−1. The ability to achieve transfer of wafer-scale single crystals with almost no deterioration of electrical properties means the present method is scalable. The demonstrations in this study show that the present transfer method can revolutionize printed electronics and constitute a key step forward in TFT fabrication processes.

Solution-Processed Inverted Organic Photovoltaics on Metal Foil Substrates

2008 ◽  
Author(s):  
W. Gaynor ◽  
J. Y. Lee ◽  
S. T. Connor ◽  
Y. Cui ◽  
P. Peumans
Keyword(s):  
Organic Photovoltaics ◽  
Metal Foil ◽  
Solution Processed

Room temperature solution processed tungsten carbide as an efficient hole extraction layer for organic photovoltaics

2014 ◽  
Vol 2 (11) ◽  
pp. 3734-3740 ◽  
Author(s):  
Wei Cui ◽  
Zhongwei Wu ◽  
Changhai Liu ◽  
Mingxing Wu ◽  
Tingli Ma ◽  
...  
Keyword(s):  
Solar Cell ◽  
Tungsten Carbide ◽  
Buffer Layer ◽  
Organic Photovoltaics ◽  
Organic Solar Cell ◽  
High Performance ◽  
Room Temperature ◽  
Solution Processed ◽  
Anode Buffer Layer ◽  
Temperature Solution

We demonstrated tungsten carbide (WC) as an efficient anode buffer layer for a high-performance inverted organic solar cell.

scholarly journals Efficient CdTe Nanocrystal/TiO2 Hetero-Junction Solar Cells with Open Circuit Voltage Breaking 0.8 V by Incorporating A Thin Layer of CdS Nanocrystal

Nanomaterials ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 614 ◽  
Author(s):  
Xianglin Mei ◽  
Bin Wu ◽  
Xiuzhen Guo ◽  
Xiaolin Liu ◽  
Zhitao Rong ◽  
...  
Keyword(s):  
Solar Cells ◽  
Thin Layer ◽  
Large Scale ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Band Alignment ◽  
Ambient Conditions ◽  
Solution Processed ◽  
Processing Technologies ◽  
Cdte Nanocrystal

Nanocrystal solar cells (NCs) allow for large scale solution processing under ambient conditions, permitting a promising approach for low-cost photovoltaic products. Although an up to 10% power conversion efficiency (PCE) has been realized with the development of device fabrication technologies, the open circuit voltage (Voc) of CdTe NC solar cells has stagnated below 0.7 V, which is significantly lower than most CdTe thin film solar cells fabricated by vacuum technology (around 0.8 V~0.9 V). To further improve the NC solar cells’ performance, an enhancement in the Voc towards 0.8–1.0 V is urgently required. Given the unique processing technologies and physical properties in CdTe NC, the design of an optimized band alignment and improved junction quality are important issues to obtain efficient solar cells coupled with high Voc. In this work, an efficient method was developed to improve the performance and Voc of solution-processed CdTe nanocrystal/TiO2 hetero-junction solar cells. A thin layer of solution-processed CdS NC film (~5 nm) as introduced into CdTe NC/TiO2 to construct hetero-junction solar cells with an optimized band alignment and p-n junction quality, which resulted in a low dark current density and reduced carrier recombination. As a result, devices with improved performance (5.16% compared to 2.63% for the control device) and a Voc as high as 0.83 V were obtained; this Voc value is a record for a solution-processed CdTe NC solar cell.

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