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CMP
Credit: Jack Hobhouse

Dr James Ball

Long Term Visitor

Sub department

  • Condensed Matter Physics
james.ball@physics.ox.ac.uk
Telephone: 01865 (2)82327
Robert Hooke Building, room G26
  • About
  • Publications

Steering perovskite precursor solutions for multijunction photovoltaics

Nature Nature Research (2024)

Authors:

Shuaifeng Hu, Junke Wang, Pei Zhao, Jorge Pascual, Jianan Wang, Florine Rombach, Akash Dasgupta, Wentao Liu, Minh Anh Truong, He Zhu, Manuel Kober-Czerny, James N Drysdale, Joel A Smith, Zhongcheng Yuan, Guus JW Aalbers, Nick RM Schipper, Jin Yao, Kyohei Nakano, Silver-Hamill Turren-Cruz, André Dallmann, M Greyson Christoforo, James M Ball, David P McMeekin, Karl-Augustin Zaininger, Zonghao Liu, Nakita K Noel, Keisuke Tajima, Wei Chen, Masahiro Ehara, René AJ Janssen, Atsushi Wakamiya, Henry J Snaith

Abstract:

Multijunction photovoltaics (PVs) are gaining prominence owing to their superior capability of achieving power conversion efficiencies (PCEs) beyond the radiative limit of single-junction cells<sup>1-8</sup>, where improving narrow bandgap tin-lead perovskites is critical for thin-film devices<sup>9</sup>. With a focus on understanding the chemistry of tin-lead perovskite precursor solutions, we herein find that Sn(II) species dominate interactions with precursors and additives and uncover the exclusive role of carboxylic acid in regulating solution colloidal properties and film crystallisation, and ammonium in improving film optoelectronic properties. Materials that combine these two function groups, amino acid salts, considerably improve the semiconducting quality and homogeneity of perovskite films, surpassing the effect of the individual functional groups when introduced as part of separate molecules. Our enhanced tin-lead perovskite layer allows us to fabricate solar cells with PCEs of 23.9, 29.7 (certified 29.26%), and 28.7% for single-, double-, and triple-junction devices, respectively. Our 1-cm<sup>2</sup> triple-junction devices show PCEs of 28.4% (certified 27.28%). Encapsulated triple-junction cells maintain 80% of their initial efficiencies after 860 h maximum power point tracking in ambient. We further fabricate quadruple-junction devices and obtain PCEs of 27.9% with the highest open-circuit voltage of 4.94 V. This work establishes a new benchmark for multijunction PVs.
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A piperidinium salt stabilizes efficient metal-halide perovskite solar cells

Science American Association for the Advancement of Science 369:6499 (2020) 96-102

Authors:

Yen-Hung Lin, Nobuya Sakai, Peimei Da, Jiaying Wu, Harry Sansom, Alexandra Ramadan, Suhas Mahesh, Junliang Liu, Robert Oliver, Jongchul Lim, Lee Aspitarte, Kshama Sharma, Pk Madhu, Anna Morales‐Vilches, Pabitra Nayak, Sai Bai, Feng Gao, Christopher Grovenor, Michael Johnston, John Labram, James Durrant, James Ball, Bernard Wenger, Bernd Stannowski, Henry Snaith

Abstract:

Longevity has been a long-standing concern for hybrid perovskite photovoltaics. We demonstrate high-resilience positive-intrinsic-negative perovskite solar cells by incorporating a piperidiniumbased ionic-compound into the formamidinium-cesium lead-trihalide perovskite absorber. With the band gap tuned to be well suited for perovskite-on-silicon tandem cells, this piperidinium additive enhances the open-circuit voltage and cell efficiency. This additive also retards compositional segregation into impurity phases and pinhole formation in the perovskite absorber layer during aggressive aging. Under full-spectrum simulated sunlight in ambient atmosphere, our Confidential unencapsulated and encapsulated cells retain 80% and 95% of their peak and “post-burn-in” efficiencies for 1010 and 1200 hours at 60 and 85 degree Celsius, respectively. Our analysis reveals detailed degradation routes that contribute to the failure of aged cells.
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Metal composition influences optoelectronic quality in mixed-metal lead-tin triiodide perovskite solar absorbers

Energy and Environmental Science Royal Society of Chemistry 13:6 (2020) 1776-1787

Authors:

Matthew Klug, Rebecca Milot, Jay Patel, Thomas Green, Harry Sansom, Michael Farrar, Alexandra Ramadan, Samuele Martani, Zhiping Wang, Bernard Wenger, James Ball, Liam Langshaw, Annamaria Petrozza, Michael Johnston, Laura Herz, Henry J Snaith

Abstract:

Current designs for all-perovskite multi-junction solar cells require mixed-metal Pb-Sn compositions to achieve narrower band gaps than are possible with their neat Pb counterparts. The lower band gap range achievable with mixed-metal Pb-Sn perovskites also encompasses the 1.3 to 1.4 eV range that is theoretically ideal for maximising the efficiency of single-junction devices. Here we examine the optoelectronic quality and photovoltaic performance of the ((HC(NH2)2)0.83Cs0.17)(Pb1-ySny)I3 family of perovskite materials across the full range of achievable band gaps by substituting between 0.001% and 70% of the Pb content with Sn. We reveal that a compositional range of "defectiveness"exists when Sn comprises between 0.5% and 20% of the metal content, but that the optoelectronic quality is restored for Sn content between 30-50%. When only 1% of Pb content is replaced by Sn, we find that photoconductivity, photoluminescence lifetime, and photoluminescence quantum efficiency are reduced by at least an order of magnitude, which reveals that a small concentration of Sn incorporation produces trap sites that promote non-radiative recombination in the material and limit photovoltaic performance. While these observations suggest that band gaps between 1.35 and 1.5 eV are unlikely to be useful for optoelectronic applications without countermeasures to improve material quality, highly efficient narrower band gap absorber materials are possible at or below 1.33 eV. Through optimising single-junction photovoltaic devices with Sn compositions of 30% and 50%, we respectively demonstrate a 17.6% efficient solar cell with an ideal single-junction band gap of 1.33 eV and an 18.1% efficient low band gap device suitable for the bottom absorber in all-perovskite multi-junction cells.
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Dual-source co-evaporation of low-bandgap FA1-xCsxSn1-yPbyI3 perovskites for photovoltaics

ACS Energy Letters American Chemical Society 4 (2019) 2748-2756

Authors:

JM Ball, L Buizza, HC Sansom, Farrar, MT Klug, J Borchert, J Patel, LM Herz, Michael Johnston, Henry Snaith
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Controlling competing photochemical reactions stabilizes perovskite solar cells

NATURE PHOTONICS 13:8 (2019) 532-+

Authors:

Silvia G Motti, Daniele Meggiolaro, Alex J Barker, Edoardo Mosconi, Carlo Andrea Riccardo Perini, James M Ball, Marina Gandini, Min Kim, Filippo De Angelis, Annamaria Petrozza
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