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Solar cells

Yunhai Zhang, Huiru Lv, Can Cui, Lingbo Xu, Peng Wang, Hao Wang, Xuegong Yu, Jiangsheng Xie, Jiabin Huang, Zeguo Tang, Deren Yang
The solution-processed polycrystalline perovskite film contributes critically to the high photovoltaic performance of perovskite based solar cells (PSCs). The inevitable electronic trap states at grain boundaries and the intrinsic defects such as metallic lead (Pb0) and halide vacancies in perovskite film cause serious carrier recombination loss. Furthermore, the film can easily decompose into PbI2 in moisture atmosphere. Here, we introduce a simple strategy through a small increase in methylammonium iodide (CH3NH3I, MAI) molar proportion (5%) for perovskite fabrication in ambient air with a ~50% relative humidity...
March 27, 2017: Nanotechnology
Fallon J M Colberts, Martijn M Wienk, René A J Janssen
Polymer solar cells based on PDPP5T and PCBM as donor and acceptor materials have been processed from aqueous nanoparticle miniemulsions. Careful monitoring and optimizing the concentration of free and surface-bound surfactants in the dispersion, by measuring the conductivity and zeta potential, is essential to avoid aggregation of nanoparticles at low concentration and de-wetting of the film at high concentration. The surfactant concentration is crucial for creating reproducible processing conditions that aid in further developing aqueous nanoparticle processed solar cells...
March 27, 2017: ACS Applied Materials & Interfaces
Yanliang Liu, Insoo Shin, In-Wook Hwang, Seungmin Kim, Jihoon Lee, Mi-Sun Yang, Yun Kyung Jung, Jae-Won Jang, Jung Hyun Jeong, Sung Heum Park, Kwang Ho Kim
We report a simple, low cost, and quite effective method for achieving single-crystal-like CH3NH3PbI3 perovskite leading to a significant enhancement in the performance and stability of inverted planar perovskite solar cells (IPSCs). By employing a merged annealing method during the fabrication of an IPSC for preparing the perovskite CH3NH3PbI3 film, we remarkably increase the crystallinity of the CH3NH3PbI3 film and enhance the device performance and stability. An IPSC with the indium tin oxide/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)/CH3NH3PbI3 (active layer)/ [6,6]-phenyl-C61-butyric acid methyl ester/Al structure was fabricated using the merged annealing method and exhibited significantly enhanced performance with a high power conversion efficiency of 18...
March 27, 2017: ACS Applied Materials & Interfaces
S Cacovich, L Ciná, F Matteocci, G Divitini, P A Midgley, A Di Carlo, C Ducati
Operational stability is the main issue hindering the commercialisation of perovskite solar cells. Here, a long term light soaking test was performed on large area hybrid halide perovskite solar cells to investigate the morphological and chemical changes associated with the degradation of photovoltaic performance occurring within the devices. Using Scanning Transmission Electron Microscopy (STEM) in conjunction with EDX analysis on device cross sections, we observe the formation of gold clusters in the perovskite active layer as well as in the TiO2 mesoporous layer, and a severe degradation of the perovskite due to iodine migration into the hole transporter...
March 27, 2017: Nanoscale
Song Chen, Peng Liu, Yong Hua, Yuanyuan Li, Lars Kloo, Xingzhu Wang, Beng S Ong, Wai-Kwok Wong, Xunjin Zhu
To develop new hole transporting materials (HTMs) for efficient and stable perovskite solar cells (PSCs), 5,10,15,20-tetrakis{4-[N,N-di(4-methoxylphenyl)amino-phenyl]}- porphyrin has been prepared in gram scale through the direct condensation of pyrrole and 4-[bis(4-methoxyphenyl)amino]benzaldehyde. Its Zn(II) and Cu(II) complexes exhibit excellent thermal and electrochemical stability, specifically, high hole mobility and very favorable energetics for hole extraction that render them a new class of HTMs in organometallic halide perovskite solar cells (PSCs)...
March 27, 2017: ACS Applied Materials & Interfaces
Yongbo Yuan, Tao Li, Qi Wang, Jie Xing, Alexei Gruverman, Jinsong Huang
Organic-inorganic hybrid perovskites (OIHPs) have been demonstrated to be highly successful photovoltaic materials yielding very-high-efficiency solar cells. We report the room temperature observation of an anomalous photovoltaic (APV) effect in lateral structure OIHP devices manifested by the device's open-circuit voltage (VOC) that is much larger than the bandgap of OIHPs. The persistent VOC is proportional to the electrode spacing, resembling that of ferroelectric photovoltaic devices. However, the APV effect in OIHP devices is not caused by ferroelectricity...
March 2017: Science Advances
Corinne Zinflou, Patrick J Rochette
Exposure to sunlight ultraviolet-A (UVA), the main component of solar UV reaching the eyes, is suspected to play an important part in the onset of ocular pathologies. UVA primary biological deleterious effects arise from the photo-induction of oxidative stress in cells. However, the molecular bases linking UVA-induced oxidation to UVA toxicity in eyes remain poorly understood, especially with regards to the cornea. To shed some light on this issue, we have investigated the susceptibility and response potential of the different corneal cellular layers (epithelium, stroma and endothelium) to UVA-induced oxidation...
March 22, 2017: Free Radical Biology & Medicine
Olof Bäcke, Camilla Lindqvist, Amaia Diaz de Zerio Mendaza, Stefan Gustafsson, Ergang Wang, Mats R Andersson, Christian Müller, Per Magnus Kristiansen, Eva Olsson
We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope...
March 15, 2017: Ultramicroscopy
Josh Baillargeon, Yuling Xie, Thomas W Hamann
A cobalt(IV/III) redox shuttle, cobalt tris(2-(p-tolyl)pyridine), [Co(ptpy)3]+/0, was synthesized and investigated for use in dye-sensitized solar cells, DSSCs. An incredibly fast self-exchange rate constant of (9.2  3.9) × 108 M-1s-1 was determined for [Co(ptpy)3]+/0, making it an ideal candidate for dye regeneration. To avoid fast recombination and solubility limitations, a tandem electrolyte containing [Co(ptpy)3]+/0 and cobalt tris(2,2'-bipyridine), [Co(bpy)3]3+/2+, was utilized. An improved short circuit current density is achieved for DSSCs employing the tandem electrolyte, compared to electrolytes containing only [Co(bpy)3]3+/2+, consistent with superior dye regeneration expected based on predictions using Marcus Theory, which is also discussed...
March 24, 2017: ACS Applied Materials & Interfaces
Wenjin Zeng, Xingming Liu, Xiangru Guo, Qiaoli Niu, Jianpeng Yi, Ruidong Xia, Yong Min
This review presents an overall discussion on the morphology analysis and optimization for perovskite (PVSK) solar cells. Surface morphology and energy alignment have been proven to play a dominant role in determining the device performance. The effect of the key parameters such as solution condition and preparation atmosphere on the crystallization of PVSK, the characterization of surface morphology and interface distribution in the perovskite layer is discussed in detail. Furthermore, the analysis of interface energy level alignment by using X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy is presented to reveals the correlation between morphology and charge generation and collection within the perovskite layer, and its influence on the device performance...
March 24, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Binrui Xu, Sai-Anand Gopalan, Anantha-Iyengar Gopalan, Nallal Muthuchamy, Kwang-Pill Lee, Jae-Sung Lee, Yu Jiang, Sang-Won Lee, Sae-Wan Kim, Ju-Seong Kim, Hyun-Min Jeong, Jin-Beon Kwon, Jin-Hyuk Bae, Shin-Won Kang
Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is most commonly used as an anode buffer layer in bulk-heterojunction (BHJ) polymer solar cells (PSCs). However, its hygroscopic and acidic nature contributes to the insufficient electrical conductivity, air stability and restricted photovoltaic (PV) performance for the fabricated PSCs. In this study, a new multifunctional additive, 2,3-dihydroxypyridine (DOH), has been used in the PEDOT: PSS buffer layer to obtain modified properties for PEDOT: PSS@DOH and achieve high PV performances...
March 24, 2017: Scientific Reports
Qi Chen, Lei Chen, Fengye Ye, Ting Zhao, Feng Tang, Adharsh Rajagopal, Zheng Jiang, Shenlong Jiang, Alex K-Y Jen, Yi Xie, Jinhua Cai, Liwei Chen
Controlled doping for adjustable material polarity and charge carrier concentration is the basis of semiconductor materials and devices, and it is much more difficult to achieve in ionic semiconductors (e.g. ZnO and GaN) than in covalent semiconductors (e.g. Si and Ge), due to the high intrinsic defect density in ionic semiconductors. The organic-inorganic perovskite material, which is frenetically being researched for applications in solar cells and beyond, is also an ionic semiconductor. Here we present the Ag-incorporated organic-inorganic perovskite films and planar heterojunction solar cells...
March 24, 2017: Nano Letters
Xiaotao Zheng, Weilin Chen, Li Chen, Yijing Wang, Xiangwei Guo, Jiabo Wang, En-Bo Wang
Polyoxometalate (POM) has already been confirmed to act as an effective electron-transfer mediator for improving the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) based on our studies. However, it may be limited by the agglomeration of the polyoxoanions. In this paper, we improve our previous synthesis strategy by breaking the MOFs with POMs as the secondary building units ([Ni(bpp)(H2O)2]3[P2W18O62]·24H2O(1) and H6[Cu3(H2O)6(P2W18O62)2(3-dpye)6]·28H2O (2)) to design and synthesize small-size and high-dispersive POM nanoparticles by means of compositing with TiO2 via the calcination to remove the organic ligand...
March 24, 2017: Chemistry: a European Journal
Hui Li, Shuwei Hao, Chunhui Yang, Guanying Chen
The ability to synthesize high-quality hierarchical core/shell nanocrystals from an efficient host lattice is important to realize efficacious photon upconversion for applications ranging from bioimaging to solar cells. Here, we describe a strategy to fabricate multicolor core @ shell α-NaLuF₄:Yb(3+)/Ln(3+)@CaF₂ (Ln = Er, Ho, Tm) upconversion nanocrystals (UCNCs) based on the newly established host lattice of sodium lutetium fluoride (NaLuF₄). We exploited the liquid-solid-solution method to synthesize the NaLuF₄ core of pure cubic phase and the thermal decomposition approach to expitaxially grow the calcium fluoride (CaF₂) shell onto the core UCNCs, yielding cubic core/shell nanocrystals with a size of 15...
February 7, 2017: Nanomaterials
Prathap Pathi, Akshit Peer, Rana Biswas
Thick wafer-silicon is the dominant solar cell technology. It is of great interest to develop ultra-thin solar cells that can reduce materials usage, but still achieve acceptable performance and high solar absorption. Accordingly, we developed a highly absorbing ultra-thin crystalline Si based solar cell architecture using periodically patterned front and rear dielectric nanocone arrays which provide enhanced light trapping. The rear nanocones are embedded in a silver back reflector. In contrast to previous approaches, we utilize dielectric photonic crystals with a completely flat silicon absorber layer, providing expected high electronic quality and low carrier recombination...
January 13, 2017: Nanomaterials
Aibin Huang, Lei Lei, Jingting Zhu, Yu Yu, Yan Liu, Songwang Yang, Shanhu Bao, Xun Cao, Ping Jin
Aiming at fabricating simple, reproducible and scalable perovskite solar cells (PSCs) with least time consuming, novel CoOx hole transport layer (HTL) was first proposed and introduced in this work. The CoOx HTL thickness was minimized to about 10 nm with complete coverage on FTO substrate (F doped SnO2) by DC magnetron sputtering. The compact ultrathin HTL could minimize the incident light loss caused by cobalt ion absorption and reduce the carrier transport loss by shortening the transport path. Copper ion doping was employed to address the low conductivity of CoOx film and the energy level mismatch between CoOx and perovskite material...
March 23, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Jae Yoon Lee, Jun-Hwan Shin, Gwan-Hyoung Lee, Chul-Ho Lee
Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDCs) and black phosphorous have drawn tremendous attention as an emerging optical material due to their unique and remarkable optical properties. In addition, the ability to create the atomically-controlled van der Waals (vdW) heterostructures enables realizing novel optoelectronic devices that are distinct from conventional bulk counterparts. In this short review, we first present the atomic and electronic structures of 2D semiconducting TMDCs and their exceptional optical properties, and further discuss the fabrication and distinctive features of vdW heterostructures assembled from different kinds of 2D materials with various physical properties...
October 27, 2016: Nanomaterials
Francis S Maloney, Uma Poudyal, Weimin Chen, Wenyong Wang
Zinc oxide nanowire and titanium dioxide nanoparticle (ZnO:TiO₂ NW/NP) hybrid films were utilized as the photoanode layer in quantum dot-sensitized solar cells (QDSSCs). CdSe quantum dots (QDs) with a ZnS passivation layer were deposited on the ZnO:TiO₂ NW/NP layer as a photosensitizer by successive ion layer adsorption and reaction (SILAR). Cells were fabricated using a solid-state polymer electrolyte and intensity-modulated photovoltage and photocurrent spectroscopy (IMVS/PS) was carried out to study the electron transport properties of the cell...
October 25, 2016: Nanomaterials
Lung-Chien Chen, Zong-Liang Tseng, Jun-Kai Huang
This work presents mixed (FAPbI₃)1-x(MAPbBr₃)x perovskite films with various composition ratios, x (x = 0-1), which are formed using the spin coating method. The structural, optical, and electronic behaviors of the mixed (FAPbI₃)1-x(MAPbBr₃)x perovskite films are discussed. A device with structure glass/indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/mixed perovskite/C60/BCP/Ag was fabricated. The mixed perovskite film was an active light-harvesting layer. PEDOT: PSS was a hole transporting layer between the ITO and perovskite...
October 13, 2016: Nanomaterials
Sofia Paulo, Emilio Palomares, Eugenia Martinez-Ferrero
Graphene and carbon quantum dots have extraordinary optical and electrical features because of their quantum confinement properties. This makes them attractive materials for applications in photovoltaic devices (PV). Their versatility has led to their being used as light harvesting materials or selective contacts, either for holes or electrons, in silicon quantum dot, polymer or dye-sensitized solar cells. In this review, we summarize the most common uses of both types of semiconducting materials and highlight the significant advances made in recent years due to the influence that synthetic materials have on final performance...
August 25, 2016: Nanomaterials
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