Details

Autor(en) / Beteiligte

• Caprioglio, Pietro
• Wolff, Christian M.
• Sandberg, Oskar J.
• Armin, Ardalan
• Rech, Bernd
• Albrecht, Steve
• Neher, Dieter
• Stolterfoht, Martin

Titel

On the Origin of the Ideality Factor in Perovskite Solar Cells

Ist Teil von

• Advanced energy materials, 2020-07, Vol.10 (27), p.n/a

Ort / Verlag

Weinheim: Wiley Subscription Services, Inc

Erscheinungsjahr

2020

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The measurement of the ideality factor (nid) is a popular tool to infer the dominant recombination type in perovskite solar cells (PSC). However, the true meaning of its values is often misinterpreted in complex multilayered devices such as PSC. In this work, the effects of bulk and interface recombination on the nid are investigated experimentally and theoretically. By coupling intensity‐dependent quasi‐Fermi level splitting measurements with drift diffusion simulations of complete devices and partial cell stacks, it is shown that interfacial recombination leads to a lower nid compared to Shockley–Read–Hall (SRH) recombination in the bulk. As such, the strongest recombination channel determines the nid of the complete cell. An analytical approach is used to rationalize that nid values between 1 and 2 can originate exclusively from a single recombination process. By expanding the study over a wide range of the interfacial energy offsets and interfacial recombination velocities, it is shown that an ideality factor of nearly 1 is usually indicative of strong first‐order non‐radiative interface recombination and that it correlates with a lower device performance. It is only when interface recombination is largely suppressed and bulk SRH recombination dominates that a small nid is again desirable. Intensity‐dependent absolute photoluminescence studies on perovskite neat materials and partial cell stacks highlight how interface recombination can account for ideality factors between 1 and 2, commonly observed in perovskite devices. The findings are rationalized via a recombination model which details how interface recombination can lead to ideality factors of unity, in this case, not representative of a better device.