Organometallic halide perovskites attract strong interests for their high photoresponsivity and solar cell efficiency. However, there was no systematic study of their power-and frequencydependent photoresponsivity. We identified two different powerdependent photoresponse types in methylammonium lead iodide perovskite (MAPbI 3 ) photodetectors. In the first type, the photoresponse remains constant from 5 Hz to 800 MHz. In the second type, absorption of a single photon can generate a persistent photoconductivity of 30 pA under an applied electric field of 2.5 × 10 4 V/ cm. Additional absorbed photons, up to 8, linearly increase the persistent photoconductivity, which saturates with the absorption of more than 10 photons. This is different than single-photon avalanche detectors (SPADs) because the single-photon response is persistent as long as the device is under bias, providing unique opportunities for novel electronic and photonic devices such as analogue memories for neuromorphic computing. We propose an avalanche-like process for iodine ions and estimate that absorption of a single 0.38 aJ photon triggers the motion of 10 8−9 ions, resulting in accumulations of ions and charged vacancies at the MAPbI 3 /electrode interfaces to cause the band bending and change of electric material properties. We have made the first observation that single-digit photon absorption can alter the macroscopic electric and optoelectronic properties of a perovskite thin film.
Minimizing iridium oxide electrodes for high visual acuity subretinal stimulation
Abbreviated Title (50 character maximum)Influence of electrode size on retinal stimulation 3. List all Author Names and Affiliations in order as they would appear in the published article
Optoelectronic retinal prostheses transduce light into electrical current for neural stimulation. We introduce a novel optoelectronic pixel architecture consisting of a vertically integrated photo junction-field-effect transistor (Photo-JFET) and neural stimulating electrode. Experimental measurements demonstrate that optically addressed Photo-JFET pixels utilize phototransistive gain to produce a broad range of neural stimulation current and can effectively stimulate retinal neurons in vitro. The compact nature of the Photo-JFET pixel can enable high resolution retinal prostheses with the smallest reported optoelectronic pixel size to help restore high visual acuity in patients with degenerative retinal diseases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.