Article
Energy & Fuels
A. Wratten, S. L. Pain, A. Yadav, E. Khorani, T. Niewelt, L. Black, G. Bartholazzi, D. Walker, N. E. Grant, J. D. Murphy
Summary: This study investigates the potential of ultra-thin HfO2 films grown by atomic layer deposition for passivating contacts to silicon. It specifically focuses on variations in film thickness and post-deposition annealing temperature. The results show that 2.2 nm thick films annealed at 475 degrees C exhibit the highest passivation quality. The effective work function of the films also decreases with decreasing thickness. A post-deposition annealing process reduces the effective work function further. The study also examines the contact resistivity in a passivating contact structure utilizing HfO2 and finds a temperature dependence on the annealing process. The lowest resistance is achieved below 375 degrees C.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Energy & Fuels
Bart Macco, Mike L. van de Poll, Bas W. H. van de Loo, Tim M. P. Broekema, Saravana B. Basuvalingam, Cristian A. A. van Helvoirt, Wilhelmus J. H. Berghuis, Roel J. Theeuwes, Nga Phung, Wilhelmus M. M. Kessels
Summary: Recently, it has been shown that stacks consisting of ultrathin SiO2 coated with ALD Al-doped zinc oxide (ZnO:Al) can achieve excellent passivation and low contact resistivity. This study investigates the required thicknesses of ZnO and Al2O3 capping layer for high passivation levels, and demonstrates selective removal of Al2O3 layer from ZnO:Al. Furthermore, it highlights the potential of spatial ALD for industrial applications and the selective deposition of ZnO:Al on oxidized regions of a c-Si surface.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Energy & Fuels
Bart Macco, Bas W. H. van de Loo, Marc Dielen, Dennis G. J. A. Loeffen, Bart B. van Pelt, Nga Phung, Jimmy Melskens, Marcel A. Verheijen, Wilhelmus M. M. Kessels
Summary: Research has shown that stacks consisting of ultrathin SiO2 coated with ALD ZnO and Al2O3 provide state-of-the-art passivation for n-type crystalline silicon surfaces and additional functionalities for silicon solar cells. The Al2O3 capping layer is crucial in the passivation mechanism, while annealing can significantly improve the transparency and lateral conductivity of ZnO.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Energy & Fuels
Xinyu Wang, Kun Gao, Dacheng Xu, Kun Li, Chunfang Xing, Xinliang Lou, Zhaojun Su, Xinbo Yang
Summary: Surface passivation is improved by using a boron oxide/aluminum oxide stack (BOx/Al2O3) on c-Si surfaces. The BOx/Al2O3 stacks show superior passivation quality compared to Al2O3 single layers after annealing. The optimized BOx/Al2O3 passivation stack achieves very low dark current densities on n-type and p-type Cz wafers, as well as boron-doped p+ emitters.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Article
Chemistry, Physical
Xiaoning Liu, Jiakai Zhou, Yi Ding, Xiaodan Zhang, Ying Zhao, Guofu Hou
Summary: In this work, the potential of hydrogenated molybdenum oxide (H:MoOx) deposited by Atomic Layer Deposition (ALD) as an efficient hole selective passivating contact for p-type crystalline silicon solar cell is demonstrated. The results show a significant impact of precursor and deposition temperature on the properties of H:MoOx thin films, leading to variations in hydrogenation degree and work function. The H:MoOx thin film as a hole selective passivating contact achieves low contact resistivity (72.6 mU cm2) and high open-circuit voltage (624 mV), resulting in an increased power conversion efficiency of the solar cell from 15.48% to 17.23%.
MATERIALS TODAY ENERGY
(2023)
Article
Energy & Fuels
Gerard Masmitja, Eloi Ros, Rosa Almache-Hernandez, Benjamin Pusay, Isidro Martin, Cristobal Voz, Edgardo Saucedo, Joaquim Puigdollers, Pablo Ortega
Summary: This study successfully demonstrates the fabrication of high efficiency IBC c-Si(n) solar cells using transition metal oxide films as carrier-selective contacts deposited by ALD technique, achieving excellent photovoltaic efficiencies and pseudo efficiencies.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Chemistry, Multidisciplinary
Armin Richter, Hemangi Patel, Christian Reichel, Jan Benick, Stefan W. Glunz
Summary: This study evaluates the effect of various plasma treatments during the ALD deposition of Al2O3/SiO2 multilayers on the passivation quality of the silicon surface. Plasma treatments after SiO2 deposition, particularly for single Al2O3/SiO2 bilayers treated with H-2 plasma, significantly improve the surface passivation quality. The improved passivation quality comes from enhanced chemical interface passivation rather than an improved field effect.
ADVANCED MATERIALS INTERFACES
(2023)
Article
Chemistry, Physical
Takuya Matsui, Shona McNab, Ruy Sebastian Bonilla, Hitoshi Sai
Summary: Dopant-free and full-area passivating hole contacts can improve the efficiency of solar cells and have the potential to simplify the manufacturing process.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Energy & Fuels
Ying Liu, Borong Sang, Md. Anower Hossain, Kun Gao, Hao Cheng, Xiaomin Song, Sihua Zhong, Linxing Shi, Wenzhong Shen, Bram Hoex, Zengguang Huang
Summary: This study investigated the application of aluminum-doped TiO2 thin films (ATO) in high-efficiency silicon solar cells. The ATO thin films were successfully prepared and their properties, including elemental analysis, thermal stability, and optical properties, were systematically studied. High effective minority carrier lifetime and low contact resistivity were achieved on silicon wafers, highlighting ATO as a promising alternative for high-efficiency crystalline silicon solar cells.
Article
Nanoscience & Nanotechnology
Abigail R. Meyer, Rohan P. Chaukulkar, Noemi Leick, William Nemeth, David L. Young, Paul Stradins, Sumit Agarwal
Summary: In this study, the atomistic-level mechanism for the chemical passivation of the monocrystalline Si surface with thermally annealed Al2O3 was investigated using in situ infrared spectroscopy and photoconductance decay measurements. The results showed that surface Si-H bonds are preserved after the ALD of Al2O3 on H-terminated Si, and restructuring occurs at the c-Si/Al2O3 interface during annealing to form interfacial SiOx. Isotope labeling was used to differentiate interfacial SiD bonds on the c-Si surface from H incorporated in Al2O3, and no net migration of atomic H or D from Al2O3 to the c-Si/Al2O3 interface was observed within the sensitivity of the infrared setup. Passivation studies were also conducted on c-Si/SiO2/Al2O3 stacks, revealing that an O-2-containing atmosphere led to the best surface chemical passivation.
ACS APPLIED NANO MATERIALS
(2021)
Article
Chemistry, Inorganic & Nuclear
Anish Philip, Lukas Mai, Ramin Ghiyasi, Anjana Devi, Maarit Karppinen
Summary: The combined atomic/molecular layer deposition (ALD/MLD) technique is an advanced synthesis route for metal-organic thin-film materials. This study introduces novel ALD/MLD processes using non-pyrophoric precursors and hydroquinone, resulting in high-quality and stable thin films deposited at low temperatures.
DALTON TRANSACTIONS
(2022)
Article
Chemistry, Physical
Eunyoung Choi, Jin-Won Lee, Miguel Anaya, Alessandro Mirabelli, Hongjae Shim, Joseph Strzalka, Jongchul Lim, Siwon Yun, Milos Dubajic, Jihoo Lim, Jan Seidel, Raphael Edem Agbenyeke, Chang Gyoun Kim, Nam Joong Jeon, Arman Mahboubi Soufiani, Helen Hejin Park, Jae Sung Yun
Summary: Long-chain organic halide salts are widely used in perovskite-based optoelectronic devices for surface passivation. By introducing aluminum oxide (AlOx) onto octylammonium iodide (OAI) through atomic layer deposition, the benefits of organic halide salts can be utilized without generating undesired defects. The OAI/AlOx devices show improved performance and photo-stability compared to the treated devices, with a diffusion of aluminum from AlOx into the perovskite contributing to uniform carrier transport. In addition, light-induced two-dimensional perovskite formation is observed on OAI/AlOx, which prevents the loss of OA cations and suppresses the light-induced degradation of the devices.
ADVANCED ENERGY MATERIALS
(2023)
Article
Chemistry, Multidisciplinary
Sophie L. Pain, Edris Khorani, Tim Niewelt, Ailish Wratten, Galo J. Paez Fajardo, Ben P. Winfield, Ruy S. Bonilla, Marc Walker, Louis F. J. Piper, Nicholas E. Grant, John D. Murphy
Summary: Ultra-thin passivating films of SiO2, Al2O3, and HfO2 were created through plasma-enhanced atomic layer deposition and annealing. It was found that thin negatively charged HfO2 layers exhibited excellent passivation properties, making them a promising candidate for future passivating contacts in high-efficiency silicon solar cells.
ADVANCED MATERIALS INTERFACES
(2022)
Article
Energy & Fuels
Bernice Mae Yu Jeco-Espaldon, Ryo Tamaki, Maxime Giteau, Hao Xu, Nazmul Ahsan, Richard R. King, Yoshitaka Okada
Summary: Perimeter recombination is one of the causes for the nonuniform luminescent coupling effect in III-V multijunction solar cells. Electrical passivation of the multijunction solar cell perimeter can significantly improve current collection and homogeneity, resulting in an increase in absolute conversion efficiency.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2023)
Review
Materials Science, Multidisciplinary
Dongchul Suh
Summary: This review discusses the latest developments in surface passivation using Al2O3/TiO2-based layers, including synthesis methods, optical properties, electrical properties, and interface engineering. The focus is on utilizing atomic-layer-deposited Al2O3/TiO2-based layers for tailoring the properties of surface passivation schemes.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Chemistry, Physical
Susanne Siebentritt, Enrico Avancini, Marcus Baer, Jakob Bombsch, Emilie Bourgeois, Stephan Buecheler, Romain Carron, Celia Castro, Sebastien Duguay, Roberto Felix, Evelyn Handick, Dimitrios Hariskos, Ville Havu, Philip Jackson, Hannu-Pekka Komsa, Thomas Kunze, Maria Malitckaya, Roberto Menozzi, Milos Nesladek, Nicoleta Nicoara, Martti Puska, Mohit Raghuwanshi, Philippe Pareige, Sascha Sadewasser, Giovanna Sozzi, Ayodhya Nath Tiwari, Shigenori Ueda, Arantxa Vilalta-Clemente, Thomas Paul Weiss, Florian Werner, Regan G. Wilks, Wolfram Witte, Max Hilaire Wolter
ADVANCED ENERGY MATERIALS
(2020)
Article
Multidisciplinary Sciences
Florian Werner, Boris Veith-Wolf, Michele Melchiorre, Finn Babbe, Jan Schmidt, Susanne Siebentritt
SCIENTIFIC REPORTS
(2020)
Article
Physics, Applied
Florian Werner, Boris Veith-Wolf, Conrad Spindler, Michael R. Barget, Finn Babbe, Jerome Guillot, Jan Schmidt, Susanne Siebentritt
PHYSICAL REVIEW APPLIED
(2020)
Article
Materials Science, Multidisciplinary
Lailah Helmich, Dominic C. Walter, Dennis Bredemeier, Jan Schmidt
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2020)
Article
Materials Science, Multidisciplinary
Marc-Uwe Halbich, Jan Schmidt
Summary: Coated n-type silicon wafers with PEDOT:PSS exhibit a drastic increase in apparent lifetime tau(app) as the excess carrier concentration Delta p decreases. By modeling the measured curves, the interface recombination velocity and band bending within the silicon induced by PEDOT:PSS can be extracted. The addition of sorbitol to the PEDOT:PSS dispersion improves chemical interface passivation without affecting band bending within the silicon bulk near the PEDOT:PSS/c-Si interface.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Valeriya Titova, Jan Schmidt
Summary: The selectivity parameter S-10 of titanium oxide-based selective contacts on n-type silicon was experimentally extracted, and the optimal annealing conditions were determined. Experimental results show that TiOx-based contacts on silicon can achieve high efficiency electron-selective contacts through appropriate processing.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Energy & Fuels
Michael Winter, Dominic C. Walter, Jan Schmidt
Summary: The article observes carrier lifetime degradation phenomena on fired gallium-doped Czochralski-grown silicon (Cz-Si:Ga) and boron-doped float-zone silicon (FZ-Si:B), noting that activation of defects responsible for degradation is triggered by different temperatures and illumination conditions. Despite differing degradation time constants for the two materials, the activation energies are within a narrow range, suggesting a novel defect formation mechanism.
IEEE JOURNAL OF PHOTOVOLTAICS
(2021)
Article
Energy & Fuels
Lailah Helmich, Dominic C. Walter, Robert Falster, Vladimir V. Voronkov, Jan Schmidt
Summary: The impact of hydrogen on boron-oxygen-related lifetime degradation and regeneration kinetics in boron-doped p-type Czochralski-grown silicon wafers was examined. It was found that hydrogen does not affect the degradation rate, but does affect the regeneration rate, with regeneration still working even without in-diffused hydrogen. This suggests that there are two distinct regeneration processes taking place.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2021)
Article
Energy & Fuels
T. Niewelt, B. Steinhauser, A. Richter, B. Veith-Wolf, A. Fell, B. Hammann, N. E. Grant, L. Black, J. Tan, A. Youssef, J. D. Murphy, J. Schmidt, M. C. Schubert, S. W. Glunz
Summary: This study characterizes and optimizes next-generation silicon solar cell concepts by accurately assessing intrinsic recombination in crystalline silicon. By fabricating high-quality silicon sample sets and considering reabsorption effects, the researchers were able to extract the lifetime limitation due to Auger recombination. The revised fundamental limiting power conversion efficiency for single-junction crystalline silicon solar cells provides greater accuracy and alignment with actual recombination processes in silicon-based photovoltaics.
SOLAR ENERGY MATERIALS AND SOLAR CELLS
(2022)
Article
Energy & Fuels
Lailah Helmich, Dominic C. Walter, Thomas Pernau, Jan Schmidt
Summary: This study examines the long-term stability of boron-doped silicon materials with different concentrations of boron and oxygen. The results show that the industrial process of firing and subsequent regeneration is effective in maintaining carrier lifetime in silicon materials.
IEEE JOURNAL OF PHOTOVOLTAICS
(2022)
Article
Physics, Applied
Dominic C. Walter, Vladimir V. Voronkov, Robert Falster, Dennis Bredemeier, Jan Schmidt
Summary: This study found that silicon samples processed with a hydrogen-rich silicon nitride layer on their surfaces can contain a high concentration of hydrogen. Dark annealing can convert the hydrogen from neutral dimers into HB pairs, rendering a significant number of boron acceptors electrically inactive. By measuring the change in specific resistivity, the concentration of inactive boron can be determined. Additionally, annealing at higher temperatures can partially revert the HB pairs back into neutral hydrogen dimers, leading to a gradual reduction in resistivity.
JOURNAL OF APPLIED PHYSICS
(2022)
Article
Multidisciplinary Sciences
Michael Winter, Dominic C. Walter, Byungsul Min, Robby Peibst, Rolf Brendel, Jan Schmidt
Summary: The fast-firing step at the end of solar cell production lines can induce light-induced degradation effects on solar cells made on different silicon materials. This study focuses on the degradation phenomena of high-efficiency solar cells with poly-Si passivating contacts made on Ga-doped Czochralski-grown silicon (Cz-Si) under elevated temperatures. The degradation extent increases with temperature up to 140 degrees C, but decreases beyond that. The degradation primarily affects the short-circuit current and fill factor, with a lesser impact on the open-circuit voltage. The degradation in these solar cells is significantly lower compared to B-doped Cz-Si wafers. Additionally, prolonged illumination at elevated temperatures can lead to improved conversion efficiency and long-term stability.
SCIENTIFIC REPORTS
(2022)
Article
Chemistry, Physical
Taowen Wang, Florian Ehre, Thomas Paul Weiss, Boris Veith-Wolf, Valeriya Titova, Nathalie Valle, Michele Melchiorre, Omar Ramirez, Jan Schmidt, Susanne Siebentritt
Summary: This study investigates the influence of backside recombination and doping level on the optical diode factor. Both experimental results and simulations indicate that both back surface recombination and high doping density can reduce the optical diode factor.
ADVANCED ENERGY MATERIALS
(2022)
Article
Multidisciplinary Sciences
Christoph Flathmann, Tobias Meyer, Valeriya Titova, Jan Schmidt, Michael Seibt
Summary: Carrier-selective and passivating SiOx/TiOy heterocontacts show great potential as alternative contacts, combining high efficiency with simpler processing. This study uses nanoscale electron microscopy to analyze well-characterized solar cells with SiOx/TiOy/Al rear contacts. The results show that annealing causes partial intermixing of the SiOx and TiOy layers, leading to a reduction in apparent thickness of the passivating SiOx. However, the electronic structure of the layers remains distinct, highlighting the importance of tailoring the processing to achieve efficient tunneling through a thin SiOx layer.
SCIENTIFIC REPORTS
(2023)
Article
Multidisciplinary Sciences
Benjamin Grimm, Sascha J. Wolter, Jan Schmidt
Summary: In this study, the contactless quasi-steady-state photoconductance (QSSPC) method was used to investigate co-evaporated methyl ammonium lead iodide (MAPbI(3)) perovskite thin films. By adapting the calibration for ultralow photoconductances, the injection-dependent carrier lifetime of the MAPbI(3) layer was extracted. It was found that the lifetime was limited by radiative recombination at high injection densities, allowing for the determination of the sum of electron and hole mobility in the MAPbI(3) using the known coefficient of radiative recombination. The combination of QSSPC measurement and transient photoluminescence measurements provided an injection-dependent lifetime curve over several orders of magnitude, from which the achievable open-circuit voltage of the examined MAPbI(3) layer was determined.
SCIENTIFIC REPORTS
(2023)
