期刊
ADVANCED FUNCTIONAL MATERIALS
卷 32, 期 41, 页码 -出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/adfm.202204825
关键词
halide segregation; hole-transport layers; metal halide perovskites; passivation; perovskite solar cells; trap states
类别
资金
- Engineering and Physical Sciences Research Council (EPSRC), Prosperity Partnership [EP/S004947/1, EP/P033229/1, EP/V010840/1]
- Oxford Photovoltaics
- Rank Prize for a Return to Research grant
- University College Oxford
- Penrose Scholarship
- TUM-IAS for a Hans Fischer Senior Fellowship and Award
This study explores the influence of a hole-transport layer in mixed-halide perovskite films on halide segregation. It shows that using a poly(triaryl)amine (PTAA) hole-extraction layer suppresses halide segregation but increases radiative recombination losses. Passivation with a piperidinium salt slows halide segregation, while a PTAA top-coating accelerates this process.
Mixed-halide perovskites offer ideal bandgaps for tandem solar cells, but photoinduced halide segregation compromises photovoltaic device performance. This study explores the influence of a hole-transport layer, necessary for a full device, by monitoring halide segregation through in situ, concurrent X-ray diffraction and photoluminescence measurements to disentangle compositional and optoelectronic changes. This work demonstrates that top coating FA(0.83)Cs(0.17)Pb(Br0.4I0.6)(3) perovskite films with a poly(triaryl)amine (PTAA) hole-extraction layer surprisingly leads to suppression of halide segregation because photogenerated charge carriers are rapidly trapped at interfacial defects that do not drive halide segregation. However, the generation of iodide-enriched regions near the perovskite/PTAA interface enhances hole back-transfer from the PTAA layer through improved energy level offsets, increasing radiative recombination losses. It is further found that while passivation with a piperidinium salt slows halide segregation in perovskite films, the addition of a PTAA top-coating accelerates such effects, elucidating the specific nature of trap types that are able to drive the halide segregation process. This work highlights the importance of selective passivation techniques for achieving efficient and stable wide-bandgap perovskite photovoltaic devices.
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