Flexible image sensor array with bulk heterojunction organic photodiode

Thick organic bulk heterojunction photodiodes with low dark current $<1\mathrm{nA}∕{\mathrm{cm}}^2$ and efficient charge collection are reported. An electric field $>1\mathrm{V}∕\mu \mathrm{m}$ is sufficient to achieve $>75\%$ charge collection in films of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-vinylene] and [6,6]-phenyl-C61-butyric acid methyl ester blends up to $4\mu \mathrm{m}$ thick, and the rate of photocurrent decay is reduced at saturation fields. The integration of a $4\mu \mathrm{m}$ thick sensor layer onto a flexible amorphous silicon thin-film transistor backplane gave an image sensor array with 35% external quantum efficiency and noise equivalent power of $30\mathrm{pW}∕{\mathrm{cm}}^2$ at reverse bias voltage of $-4\mathrm{V}$ .