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Daniel A Jacobs, Yiliang Wu, Heping Shen, Chog Barugkin, Fiona J Beck, Thomas P White, Klaus Weber, Kylie R Catchpole
The issue of hysteresis in perovskite solar cells has now been convincingly linked to the presence of mobile ions within the perovskite layer. Here we test the limits of the ionic theory by attempting to account for a number of exotic characterization results using a detailed numerical device model that incorporates ionic charge accumulation at the perovskite interfaces. Our experimental observations include a temporary enhancement in open-circuit voltage following prolonged periods of negative bias, dramatically S-shaped current-voltage sweeps, decreased current extraction following positive biasing or "inverted hysteresis", and non-monotonic transient behaviours in the dark and the light...
January 12, 2017: Physical Chemistry Chemical Physics: PCCP
Xuhui Zhang, Jiajiu Ye, Liangzheng Zhu, Haiying Zheng, Guozhen Liu, Xuepeng Liu, Bin Duan, Xu Pan, Songyuan Dai
Two-step deposition has been widely used in the perovskite layer preparation for perovskite solar cells due to its attractive morphology controllability. However, the limited diffusivity of CH3NH3I (MAI) might cause some PbI2 to remain in the perovskite film. The residual PbI2 in the perovskite film would lead to inferior performance of devices, such as, low power conversion efficiency (PCE), poor reproducibility and weak air stability. In this work, we developed a sandwich structure MAI-PbI2-MAI precursor film to prepare a PbI2-free CH3NH3PbI3 perovskite film...
January 11, 2017: Nanoscale
Xiaoyu Zhang, Hong Lin, He Huang, Claas Reckmeier, Yu Zhang, Wallace C H Choy, Andrey L Rogach
No abstract text is available yet for this article.
January 11, 2017: Nano Letters
Aibin Huang, Lei Lei, Jingting Zhu, Yu Yu, Yan Liu, Songwang Yang, Shanhu Bao, Xun Cao, Ping Jin
The short circuit current density of perovskite solar cell (PSC) was boosted by modulating the dominated plane facets of TiO2 electron transport layer (ETL). Under optimized condition, TiO2 with dominant {001} facets showed (i) low incident light loss, (ii) highly smooth surface and excellent wettability for precursor solution, (iii) efficient electron extraction and (iv) high conductivity in perovskite photovoltaic application. A current density of 24.19 mA•cm-2 was achieved as a value near the maximum limit...
January 10, 2017: ACS Applied Materials & Interfaces
Jun Kang, Lin-Wang Wang
The formation energies and charge transition levels of intrinsic point defects in lead halide perovskite CsPbBr3 are studied from first-principles calculations. It is shown that the formation energy of dominant defect under Br-rich growth condition is much lower than that under moderate or Br-poor conditions. Thus avoiding the Br-rich condition can help to reduce the defect concentration. Interestingly, CsPbBr3 is found to be highly defect tolerant in terms of its electronic structure. Most of the intrinsic defects induce shallow transition levels...
January 10, 2017: Journal of Physical Chemistry Letters
Qian Li, Shourui Li, Kai Wang, Zewei Quan, Yue Meng, Bo Zou
Searching for nontoxic and stable perovskite-like alternatives to lead-based halide perovskites for photovoltaic application is one urgent issue in photoelectricity science. Such exploration inevitably requires an effective method to accurately control both the crystalline and electronic structures. This work applies high pressure to narrow the band gap of perovskite-like organometal halide, [NH3-(CH2)4-NH3]CuCl4 (DABCuCl4), through the crystalline-structure tuning. The band gap keeps decreasing below ~12 GPa, involving with the shrinkage and distortion of CuCl42-...
January 10, 2017: Journal of Physical Chemistry Letters
Xiaoming Li, Fei Cao, Dejian Yu, Jun Chen, Zhiguo Sun, Yalong Shen, Ying Zhu, Lin Wang, Yi Wei, Ye Wu, Haibo Zeng
The recent success of organometallic halide perovskites (OHPs) in photovoltaic devices has triggered lots of corresponding research and many perovskite analogues have been developed to look for devices with comparable performance but better stability. Upon the preparation of all inorganic halide perovskite nanocrystals (IHP NCs), research activities have soared due to their better stability, ultrahigh photoluminescence quantum yield (PL QY), and composition dependent luminescence covering the whole visible region with narrow line-width...
January 9, 2017: Small
Dongdong Dong, Hui Deng, Chao Hu, Huaibing Song, Keke Qiao, Xiaokun Yang, Jian Zhang, Fensha Cai, Jiang Tang, Haisheng Song
To date, all the lead halide based full-inorganic or organic-inorganic hybrid perovskites have been synthesized from organic solvent, such as N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO), by a solution method. Herein, water has been utilized as a 'green' solvent to develop an efficient synthetic route to grow various kinds of lead halide perovskite nanowires (NWs). By controlling the proportion of the hybrid cations, Csx(CH3NH3)1-xPbI3 perovskite NWs were successfully synthesized. Every Csx(CH3NH3)1-xPbI3 perovskite NW demonstrated single crystal characteristics with uniform stoichiometric element distribution...
January 9, 2017: Nanoscale
Susana García-Martín, Keisuke Manabe, Esteban Urones-Garrote, David Ávila-Brande, Noriya Ichikawa, Yuichi Shimakawa
Perovskite-related GdBaMnFeO5 and the corresponding oxidized phase GdBaMnFeO6, with long-range layered-type ordering of the Ba and Gd atoms have been synthesized. Oxidation retains the cation ordering but drives a modulation of the crystal structure associated with the incorporation of the oxygen atoms between the Gd layers. Oxidation of GdBaMnFeO5 increases the oxidation state of Mn from 2+ to 4+, while the oxidation state of Fe remains 3+. Determination of the crystal structure of both GdBaMnFeO5 and GdBaMnFeO6 is carried out at atomic resolution by means of a combination of advanced transmission electron microscopy techniques...
January 9, 2017: Inorganic Chemistry
Holly F Zarick, Abdelaziz Boulesbaa, Alexander A Puretzky, Eric M Talbert, Zachary R DeBra, Naiya Soetan, David B Geohegan, Rizia Bardhan
In this work, we examine the impact of hybrid bimetallic Au/Ag core/shell nanostructures on the carrier dynamics of methylammonium lead tribromide (MAPbBr3) mesoporous perovskite solar cells (PSCs). Plasmon-enhanced PSCs incorporated with Au/Ag nanostructures demonstrated improved light harvesting and increased power conversion efficiency by 26% relative to reference devices. Two complementary spectral techniques, transient absorption spectroscopy (TAS) and time-resolved photoluminescence (trPL), were employed to gain a mechanistic understanding of plasmonic enhancement processes...
January 9, 2017: Nanoscale
K O Brinkmann, J Zhao, N Pourdavoud, T Becker, T Hu, S Olthof, K Meerholz, L Hoffmann, T Gahlmann, R Heiderhoff, M F Oszajca, N A Luechinger, D Rogalla, Y Chen, B Cheng, T Riedl
The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide...
January 9, 2017: Nature Communications
Ji-Hyun Cha, Jae Hoon Han, Wenping Yin, Cheolwoo Park, Yongmin Park, Tae Kyu Ahn, Jeong Ho Cho, Duk-Young Jung
High-quality and millimeter-sized perovskite single crystals of CsPbBr3 and Cs4PbBr6 were prepared in organic solvents and studied for correlation between photocurrent generation and photoluminescence (PL) emission. The CsPbBr3 crystals, which have a 3D perovskite structure, showed a highly sensitive photoresponse and poor PL signal. In contrast, Cs4PbBr6 crystals, which have a 0D perovskite structure, exhibited more than one order of magnitude higher PL intensity than CsPbBr3, which generated an ultralow photoresponse under illumination...
January 9, 2017: Journal of Physical Chemistry Letters
Baodan Zhao, Mojtaba Abdi-Jalebi, Maxim Tabachnyk, Hugh Glass, Varun S Kamboj, Wanyi Nie, Andrew J Pearson, Yuttapoom Puttisong, Karl C Gödel, Harvey E Beere, David A Ritchie, Aditya D Mohite, Siân E Dutton, Richard H Friend, Aditya Sadhanala
Low-bandgap CH3 NH3 (Pbx Sn1-x )I3 (0 ≤ x ≤ 1) hybrid perovskites (e.g., ≈1.5-1.1 eV) demonstrating high surface coverage and superior optoelectronic properties are fabricated. State-of-the-art photovoltaic (PV) performance is reported with power conversion efficiencies approaching 10% in planar heterojunction architecture with small (<450 meV) energy loss compared to the bandgap and high (>100 cm(2) V(-1) s(-1) ) intrinsic carrier mobilities.
January 2017: Advanced Materials
Rahim Munir, Arif D Sheikh, Maged Abdelsamie, Hanlin Hu, Liyang Yu, Kui Zhao, Taesoo Kim, Omar El Tall, Ruipeng Li, Detlef-M Smilgies, Aram Amassian
Solution-processed hybrid perovskite semiconductors attract a great deal of attention, but little is known about their formation process. The one-step spin-coating process of perovskites is investigated in situ, revealing that thin-film formation is mediated by solid-state precursor solvates and their nature. The stability of these intermediate phases directly impacts the quality and reproducibility of thermally converted perovskite films and their photovoltaic performance.
January 2017: Advanced Materials
Javad Shamsi, Ahmed L Abdelhady, Sara Accornero, Milena Arciniegas, Luca Goldoni, Ajay Ram Srimath Kandada, Annamaria Petrozza, Liberato Manna
We report chemical routes for the synthesis of both nanocrystals and bulk crystals of methylammonium (MA) lead halide perovskites employing N-methylformamide (NMF) as a source of MA ions. Colloidal nanocrystals were prepared by a transamidation reaction between NMF and an alkyl amine (oleylamine). The nanocrystals showed photoluminescence quantum yields reaching 74% for MAPbBr3 and 60% for MAPbI3. Bulk crystals were grown at room temperature, with no need for an antisolvent, by the acid hydrolysis of NMF. Important advantages of using NMF instead of MA salts are that the syntheses involve fewer steps and less toxic and less expensive chemicals...
November 11, 2016: ACS Energy Lett
Christopher N Savory, Aron Walsh, David O Scanlon
The methylammonium lead halides have become champion photoactive semiconductors for solar cell applications; however, issues still remain with respect to chemical instability and potential toxicity. Recently, the Cs2AgBiX6 (X = Cl, Br) double perovskite family has been synthesized and investigated as stable nontoxic replacements. We probe the chemical bonding, physical properties, and cation anti-site disorder of Cs2AgBiX6 and related compounds from first-principles. We demonstrate that the combination of Ag(I) and Bi(III) leads to the wide indirect band gaps with large carrier effective masses owing to a mismatch in angular momentum of the frontier atomic orbitals...
November 11, 2016: ACS Energy Lett
S Carretero-Palacios, A Jiménez-Solano, H Míguez
In this Perspective we discuss the implications of employing metal particles of different shape, size, and composition as absorption enhancers in methylammonium lead iodide perovskite solar cells, with the aim of establishing some guidelines for the future development of plasmonic resonance-based photovoltaic devices. Hybrid perovskites present an extraordinarily high absorption coefficient which, as we show here, makes it difficult to extrapolate concepts and designs that are applied to other solution-processed photovoltaic materials...
July 8, 2016: ACS Energy Lett
Junwen Li, Paul M Haney
We study the circular photogalvanic effect in the organometal halide perovskite solar cell absorber CH3NH3PbI3. The calculated photocurrent density for a system with broken inversion symmetry is about 10(-9) A/W, comparable to the previously studied quantum well and bulk Rashba systems. The circular photogalvanic effect relies on inversion symmetry breaking, so that by tuning the optical penetration depth, the degree of inversion symmetry breaking can be probed at different depths from the sample surface. We propose that measurements of this effect may clarify the presence or absence of inversion symmetry, which remains a controversial issue and has been argued to play an important role in the high conversion efficiency of this material...
November 2016: Applied Physics Letters
Jeong-Suong Yang, Yunsung Kang, Inyoung Kang, Seungmo Lim, Seung-Joo Shin, Jungwon Lee, Kangheon Hur
The degradation of Niobium-doped lead zirconate titanate (PZT) and two types of PZT thin films were investigated. Undoped PZT, 2-step PZT and heavily Nb-doped PZT (PNZT) around the morphotropic phase boundary (MPB) were in-situ deposited under optimum condition by RF-magnetron sputtering. All 2 μm thick films had dense perovskite columnar grain structure and self-polarized (100) dominant orientation. PZT thin films were deposited on Pt/TiOx bottom electrode on Si wafer, and Nb doped PZT thin film was on Ir/TiW electrode with help of orientation control...
January 4, 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
Guang Yang, Hongwei Lei, Hong Tao, Xiaolu Zheng, Junjie Ma, Qin Liu, Weijun Ke, Zhiliang Chen, Liangbin Xiong, Pingli Qin, Zhao Chen, Minchao Qin, Xinhui Lu, Yanfa Yan, Guojia Fang
Despite the rapid increase of efficiency, perovskite solar cells (PSCs) still face some challenges, one of which is the current-voltage hysteresis. Herein, it is reported that yttrium-doped tin dioxide (Y-SnO2 ) electron selective layer (ESL) synthesized by an in situ hydrothermal growth process at 95 °C can significantly reduce the hysteresis and improve the performance of PSCs. Comparison studies reveal two main effects of Y doping of SnO2 ESLs: (1) it promotes the formation of well-aligned and more homogeneous distribution of SnO2 nanosheet arrays (NSAs), which allows better perovskite infiltration, better contacts of perovskite with SnO2 nanosheets, and improves electron transfer from perovskite to ESL; (2) it enlarges the band gap and upshifts the band energy levels, resulting in better energy level alignment with perovskite and reduced charge recombination at NSA/perovskite interfaces...
January 2017: Small
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