Anomalous photovoltaic effect in organic-inorganic hybrid perovskite solar cells.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 28345043.
- Also identified by DOI 10.1126/sciadv.1602164 and PMC identifier 5357127.
- Licence recorded as CC BY-NC.
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Abstract
Organic-inorganic hybrid perovskites (OIHPs) have been demonstrated to be highly successful photovoltaic materials yielding very-high-efficiency solar cells. We report the room temperature observation of an anomalous photovoltaic (APV) effect in lateral structure OIHP devices manifested by the device's open-circuit voltage (<i>V</i><sub>OC</sub>) that is much larger than the bandgap of OIHPs. The persistent <i>V</i><sub>OC</sub> is proportional to the electrode spacing, resembling that of ferroelectric photovoltaic devices. However, the APV effect in OIHP devices is not caused by ferroelectricity. The APV effect can be explained by the formation of tunneling junctions randomly dispersed in the polycrystalline films, which allows the accumulation of photovoltage at a macroscopic level. The formation of internal tunneling junctions as a result of ion migration is visualized with Kelvin probe force microscopy scanning. This observation points out a new avenue for the formation of large and continuously tunable <i>V</i><sub>OC</sub> without being limited by the materials' bandgap.