Characterization of Charge Collection in Photodiodes under Mechanical Strain: Comparison between Organic Bulk Heterojunction and Amorphous Silicon

Abstract

Both gradual electrical changes and device failure mechanisms caused by mechanical strain in organic photodiodes are investigated and compared to a‐Si:H deposited on plastic substrates.

Structural origins of intrinsic stress in amorphous silicon thin films

“…Two trends in our data are consistent with conclusions of other studies that applied mechanical stress to a-Si films at room temperature: (1) failure under tension occurs at lower absolute stress levels than under compression, [38][39][40][41][42] and (2) the absolute magnitude of compressive stress possible without failure is on the order of 1 GPa. 39,40,42 …”

Electrical characteristics of lead iodide crystal devices on flexible substrate under mechanical tensile strain

“…Actually, more than five samples were measured for each of the D1 and D2 devices to confirm the electrical behavior. This behavior was also observed in ZnO nanowire , graphene (GLs) , organic photosensitive material poly [2‐methoxy‐5‐(2‐ethylhexyloxy)‐1, 4‐phenylene‐vinylene] (MEHPPV) and [6,6]‐phenyl C61‐butyric acid methyl ester (PCBM) blends and organic rubrene crystals . ZnO is a material that simultaneously has semiconducting and piezoelectric properties.…”

“…In order to confirm the electrical behavior related with the variation of band structure, the optical absorption spectra of PbI 2 crystal slices assembled on PET substrate were measured (SHIMADZU 2550 UV–Vis spectrophotometers) under flat and bent conditions with a homemade fixture. The value of the bandgap E g = 2.28 eV was determined from αhν = B ( hν − E g ) m , where α is the absorbance, hν is the incident photon energy, B is a constant, and m is a constant taking the value 1/2 when the material is a direct‐bandgap semiconductor . Figure a shows the ( αhν ) 2 versus hν plot of the devices under different tensile strain.…”

“…It is thought that the bond length and bond angle were distorted during the bending operation, causing a perturbation of the density of states at the band edge – increasing structural disorder results in widening of the band‐tail state . This behavior was thoroughly investigated in amorphous silicon theoretically and experimentally, thin‐film ZnO and organic photosensitive material . A probable interpretation for the resistivity change of the crystal under tensile strain is the electron transferring among the energy valleys, which was studied and concluded in germanium and silicon under uniaxial strain .…”

A high performance semitransparent organic photodetector with green color selectivity

“…1 Moreover, OPDs need no color filter system due to narrow absorption spectrum of organic materials and transparent OPDs can be used for compact, lightweight, and high resolution full color image sensors by stacking two or more color selective OPDs vertically. 2 In complementary metalÀoxideÀsemiconductor (CMOS) image sensors, the transparent OPDs which detect one of three primary colors or more can be integrated with silicon photodetectors.…”