Organic Photodiodes: The Future of Full Color Detection and Image Sensing

Abstract

Major growth in the image sensor market is largely as a result of the expansion of digital imaging into cameras, whether stand-alone or integrated within smart cellular phones or automotive vehicles. Applications in biomedicine, education, environmental monitoring, optical communications, pharmaceutics and machine vision are also driving the development of imaging technologies. Organic photodiodes (OPDs) are now being investigated for existing imaging technologies, as their properties make them interesting candidates for these applications. OPDs offer cheaper processing methods, devices that are light, flexible and compatible with large (or small) areas, and the ability to tune the photophysical and optoelectronic properties - both at a material and device level. Although the concept of OPDs has been around for some time, it is only relatively recently that significant progress has been made, with their performance now reaching the point that they are beginning to rival their inorganic counterparts in a number of performance criteria including the linear dynamic range, detectivity, and color selectivity. This review covers the progress made in the OPD field, describing their development as well as the challenges and opportunities.

Charge-integrating organic heterojunction phototransistors for wide-dynamic-range image sensors

“…The channel of our device (Fig. 1c) is composed of DNTT thermally evaporated on top of printed poly(N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)): [6,6]-phenyl-C 71 -butyric acid methyl ester (PCDTBT:PC 71 BM), a broad-absorption BHJ with high internal quantum efficiency 40 .…”

“…Printable photodetectors, including phototransistors and photodiodes, have potential for the creation of low-cost but high-performance image sensors on flexible substrates [4][5][6][7][8][9][10][11][12] , and could open new methods of imaging not possible with rigid substrates 13,14 . Phototransistors produce photoconductive gain, which is not seen in photodiodes, and results in external quantum efficiencies (EQEs) well over 100% (refs 15-20).…”

Insights into the Failure Mechanisms of Organic Photodetectors

“…[2] These unique properties lead to the development of a range of new products including portable fingerprint sensors, motion or object detectors, human machine interfaces, e-skin or systems for medical imaging.…”

Non-dissipative internal optical filtering with solution-grown perovskite single crystals for full-colour imaging

“…This natural system is mimicked in three-colour arrays made from Bayer or similar dissipative filters that are selected complimentarily according to a subtractive colour model ( Figure 1a). 4 Although such filters are ubiquitous in technological applications, they suffer from high losses (~2/3 of the total light flux) due to the absorption of light by the filters that cannot be further used. 5,6 In 1999, Merrill 6,7 proposed a novel solution: to stack alternatively doped silicon layers vertically rather than laterally.…”