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CMP
Credit: Jack Hobhouse

Xinyi Shen

Graduate Student

Research theme

  • Photovoltaics and nanoscience

Sub department

  • Condensed Matter Physics

Research groups

  • Snaith group
xinyi.shen@physics.ox.ac.uk
Robert Hooke Building, room G26
  • About
  • Publications

Bandgap-universal passivation enables stable perovskite solar cells with low photovoltage loss

Science American Association for the Advancement of Science 384:6697 (2024) 767-775

Authors:

Yen-Hung Lin, Vikram, Fengning Yang, Xue-Li Cao, Akash Dasgupta, Robert DJ Oliver, Aleksander M Ulatowski, Melissa M McCarthy, Xinyi Shen, Qimu Yuan, M Greyson Christoforo, Fion Sze Yan Yeung, Michael B Johnston, Nakita K Noel, Laura M Herz, M Saiful Islam, Henry J Snaith

Abstract:

The efficiency and longevity of metal-halide perovskite solar cells are typically dictated by nonradiative defect-mediated charge recombination. In this work, we demonstrate a vapor-based amino-silane passivation that reduces photovoltage deficits to around 100 millivolts (>90% of the thermodynamic limit) in perovskite solar cells of bandgaps between 1.6 and 1.8 electron volts, which is crucial for tandem applications. A primary-, secondary-, or tertiary-amino–silane alone negatively or barely affected perovskite crystallinity and charge transport, but amino-silanes that incorporate primary and secondary amines yield up to a 60-fold increase in photoluminescence quantum yield and preserve long-range conduction. Amino-silane–treated devices retained 95% power conversion efficiency for more than 1500 hours under full-spectrum sunlight at 85°C and open-circuit conditions in ambient air with a relative humidity of 50 to 60%.

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Dataset-chloride-based additive engineering for efficient and stable wide-bandgap perovskite solar cells

University of Oxford (2024)

Abstract:

Data and figures generated for the manuscript 'Chloride-based additive engineering for efficient and stable wide-bandgap perovskite solar cells'.
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Chloride-based additive engineering for efficient and stable wide-bandgap perovskite solar cells

Advanced Materials Wiley 35:30 (2023) e2211742

Authors:

Xinyi Shen, Benjamin M Gallant, Philippe Holzhey, Joel A Smith, Karim A Elmestekawy, Zhongcheng Yuan, Pvgm Rathnayake, Stefano Bernardi, Akash Dasgupta, Ernestas Kasparavicius, Tadas Malinauskas, Pietro Caprioglio, Oleksandra Shargaieva, Yen-Hung Lin, Melissa M McCarthy, Eva Unger, Vytautas Getautis, Asaph Widmer-Cooper, Laura M Herz, Henry J Snaith

Abstract:

Metal halide perovskite based tandem solar cells are promising to achieve power conversion efficiency beyond the theoretical limit of their single-junction counterparts. However, overcoming the significant open-circuit voltage deficit present in wide-bandgap perovskite solar cells remains a major hurdle for realizing efficient and stable perovskite tandem cells. Here, a holistic approach to overcoming challenges in 1.8 eV perovskite solar cells is reported by engineering the perovskite crystallization pathway by means of chloride additives. In conjunction with employing a self-assembled monolayer as the hole-transport layer, an open-circuit voltage of 1.25 V and a power conversion efficiency of 17.0% are achieved. The key role of methylammonium chloride addition is elucidated in facilitating the growth of a chloride-rich intermediate phase that directs crystallization of the desired cubic perovskite phase and induces more effective halide homogenization. The as-formed 1.8 eV perovskite demonstrates suppressed halide segregation and improved optoelectronic properties.
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Open-circuit and short-circuit loss management in wide-gap perovskite p-i-n solar cells

Nature communications Springer Nature 14:1 (2023) 932

Authors:

Pietro Caprioglio, Joel A Smith, Robert DJ Oliver, Akash Dasgupta, Saqlain Choudhary, Michael D Farrar, Alexandra J Ramadan, Yen-Hung Lin, M Greyson Christoforo, James M Ball, Jonas Diekmann, Jarla Thiesbrummel, Karl-Augustin Zaininger, Xinyi Shen, Michael B Johnston, Dieter Neher, Martin Stolterfoht, Henry J Snaith

Abstract:

In this work, we couple theoretical and experimental approaches to understand and reduce the losses of wide bandgap Br-rich perovskite pin devices at open-circuit voltage (VOC) and short-circuit current (JSC) conditions. A mismatch between the internal quasi-Fermi level splitting (QFLS) and the external VOC is detrimental for these devices. We demonstrate that modifying the perovskite top-surface with guanidinium-Br and imidazolium-Br forms a low-dimensional perovskite phase at the n-interface, suppressing the QFLS-VOC mismatch, and boosting the VOC. Concurrently, the use of an ionic interlayer or a self-assembled monolayer at the p-interface reduces the inferred field screening induced by mobile ions at JSC, promoting charge extraction and raising the JSC. The combination of the n- and p-type optimizations allows us to approach the thermodynamic potential of the perovskite absorber layer, resulting in 1 cm2 devices with performance parameters of VOCs up to 1.29 V, fill factors above 80% and JSCs up to 17 mA/cm2, in addition to a thermal stability T80 lifetime of more than 3500 h at 85 °C.

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