期刊
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
卷 11, 期 16, 页码 6505-6512出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpclett.0c01820
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类别
资金
- Royal Society (Newton International Fellowship) [NF170520]
- Cambridge Trust
- Royal Society
- Tata Group [UF150033]
- EPSRC [EP/T02030X/1, EP/R023980/1]
- European Research Council under the European Union's Horizon 2020 research and innovation programme (HYPERION) [756962]
- EPSRC [EP/T02030X/1, EP/M005143/1, EP/R023980/1] Funding Source: UKRI
It is common practice in the lead halide perovskite solar cell field to add a small molar excess of lead iodide (PbI2) to the precursor solution to increase the device performance. However, recent reports have shown that an excess of PbI2 can accelerate performance loss. In addition, PbI2 is photoactive (band gap similar to 2.3 eV), which may lead to parasitic absorption losses in a solar cell. Here we show that devices using small quantities of excess PbI2 exhibit better device performance as compared with stoichiometric devices, both initially and for the duration of a stability test under operating conditions, primarily by enhancing the charge extraction. However, the photolysis of PbI2 negates the beneficial effect on charge extraction by leaving voids in the perovskite film and introduces trap states that are detrimental for device performance. We propose that although excess PbI2 provides a good template for enhanced performance, the community must continue to seek other additives or synthesis routes that fulfill the same beneficial role as excess PbI2, but without the photolysis that negates these beneficial effects under long-term device operation.
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