Metal Halide Perovskite-Containing Multijunction Photovoltaics

 

Metal Halide Perovskite-Containing Multijunction Photovoltaics

 

Date: 5^th February, 2026 (Thursday)

Time: 11 - 11:50 am (HKT)

 

Venue: Lecture Theatre P4, Chong Yuet Ming Physics Building

 

 

University of Oxford

 

Metal halide perovskite is a class of ABX_3-type crystalline materials − in most cases − with the A being both the organic (e.g., formamidinium, methylammonium) and inorganic (e.g., Cs⁺) monovalent cations, B being divalent cations, e.g., Pb²⁺, Sn²⁺, or their mixture, and X being the halide anions, e.g., I⁻, Br⁻, and/or Cl⁻. Thanks to their superior bandgap tunability and high absorption coefficient, metal halide perovskites show great potential for fabricating single- and multi-junction photovoltaics capable of achieving high power conversion efficiencies at low cost^[1,2,3].

 

In this seminar, we will first introduce the fundamentals of hybrid perovskite materials and their thin-film processing protocols for the fabrication of solar cell devices^[4]. Then, we will exemplify the research with our recent investigations on a specific narrow bandgap (~1.25 eV) perovskite material, i.e., mixed tin−lead perovskites, and their single-junction solar cells, covering the control of the Sn(II) oxidation^[5], interface carrier extraction^[6,7], and in-situ surface reaction^[8], as well as the understanding of the solution chemistry and resultant thin-film crystallization^[9,10], from experimental and theoretical aspects. Building on the development of a full range of wide bandgap neat lead perovskites (from ~1.5 to ~2.0 eV), in the end, we will showcase the integration of these perovskite sub-cells into “all-perovskite” monolithic two-terminal double-, triple-, and first-ever quadruple-junction solar cells, with the best power conversion efficiencies of approaching 30% and photovoltage values of up to 4.94 V^[9]. In addition, we will discuss the longevity limits of this emerging multi-junction photovoltaics and propose promising strategies for enhancing the light and temperature stability of the involved sub-cells. Furthermore, we will also share insights and recent progress obtained in “perovskite-on-silicon” multi-junction cells.

 

Figure 1. A, Cross-sectional scanning electron microscopy (SEM, scale bar 1 µm) images and B, current density-voltage (J–V) curves of the all-perovskite monolithic two-terminal single-, double-, triple-, and quadruple-junction solar cells. C. External quantum efficiency (EQE) spectra of single-junction cells at different bandgaps developed for the multijunction cells. Adapted from reference 9.

 

[1] G. E. Eperon, et al., Nat. Rev. Chem. 2017, 1, 0095.

[2] S. Hu et al., Chem. Rev. 2024, 124, 4079–4123.

[3] S. Hu & H. J. Snaith, Nature 2025, 648, 544–546.

[4] Z. Li et al., Nat. Rev. Mater. 2018, 3, 18017.

[5] S. Hu et al., Chem. Sci. 2021, 12, 13513–13519.

[6] S. Hu et al., Energy Environ. Sci. 2022, 15, 2096–2107.

[7] S. Hu et al., ACS Appl. Mater. Interfaces 2022, 14, 56290–56297.

[8] S. Hu et al., Adv. Mater. 2023, 35, 2208320.

[9] S. Hu et al., Nature 2025, 639, 93–101.

[10] S. Hu et al., Angew. Chem. Int. Ed. 2025, e202514010.