The Role of Oxide Layer on the Gain Enhancement in Hybrid Perovskite Photodetectors
Marius Franckevičius a, Rokas Gegevičius a, Marius Treideris a, Vidmantas Gulbinas a
a Center for Physical Sciences and Technology, LT, Savanorių prospektas, 231, Vilnius, Lithuania
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV18)
Benidorm, Spain, 2018 May 28th - 31st
Organizers: Emilio Palomares and Rene Janssen
Poster, Marius Franckevičius, 207
Publication date: 21st February 2018

A high achievable efficiency of the perovskite-based solar cells, currently reaching almost 23% [1], shows that carrier generation efficiency in perovskites may approach 100%, suggesting that perovskites are promising materials not only for solar cells but also for sensitive photodetectors. Even though the current development of hybrid perovskite  photodetectors makes them competitive with their inorganic analogs, a detailed fundamental understanding of their operating principles is still lacking. Here, we study the performance of plain polycrystalline perovskite photodetectors fabricated on interdigitated comb electrodes made from various metals: gold, platinum and chromium. We demonstrate that a hole blocking oxide layer between metal electrodes and perovskite may enhance the device responsivity and photocurrent gain by order of magnitude. Application of Cr electrodes with naturally formed oxide layer enabled to reach an external gain of more than 350 and response time of about 5 milliseconds. We suggest that the gain enhancement originates from the hindered extraction of photogenerated holes and the migration of ions, which creates additional hole traps at interfaces. These effects reduce the barrier for electron injection and enable the passage of a larger number of electrons during the prolonged lifetime of photogenerated holes. The achieved photodetector sensitivity, suggested gain enhancement approach and obtained better understanding of the photocurrent gain mechanism in organic–inorganic metal halide perovskites open a way towards the further development of a cheap and easily fabricable planar perovskite detectors based on interdigitated electrode arrays. 

 

Reference

[1] National Renewable Energy Laboratory. Best Research-Cell Efficiencies. Available at https://www.nrel.gov/pv/assets/images/efficiency-chart.png. Accessed on 25 February 2018

 

 

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