Multication Tin-Lead Perovskite Photodiodes with Engineered Lattice Strain for Ultrasensitive Broadband Photodetection

摘要

Tin-lead alloyed perovskites with broadband absorption over 1000 nm, are suitablefor UV-vis-NIR light detection that rivals the crystalline silicon semiconductors.These alloyed perovskites usually experience local lattice distortion andinherent lattice strain, which affect the electronic band structures and introducedetrimental trap states subsequently. To date, the lattice strain and its impact onthe physical properties of tin-lead alloyed perovskites are still less understood.Herein, it is shown that the lattice strain contributes substantially to the bandedge electronic structure of multication tin-lead alloyed perovskites by tilting themetal halide octahedral configuration. It has been found that the release of latticestrain heavily affects the band edge electronic structure of tin-lead alloyed perovskitesby reducing the band tail and shallow trap states as well as narrowing thebandgap simultaneously. Leveraging these insights, the optimized photodetectorimproves nearly 10-fold the light detection limit to 0.49 pW cm~(?2), achieving arecord detectivity of >6 × 10~(12) Jones in the near-infrared range. The photodetectorson flexible substrates can be further integrated into an amplifier-freewearable photoplethysmography device for real-time heart rate and blood oxygensaturation monitoring, showing the promising potential for real applications.