A large and growing number of applications benefit from innovative and powerful 3D image sensors. Graphene photodetectors can achieve 3D sensing functionalities by intrinsic optoelectronic frequency mixing due to the nonlinear output characteristics of the sensor. In first proof of principle distance measurement demonstrations, we achieve modulation frequencies of 3.1 MHz, signal-to-noise ratios of ∼40 dB, distance detection up to at least 1 m, and a mean accuracy of 25.6 mm. The scalable More than Moore detector approach enables geometrical fill factors close to 100% and can easily complement powerful functionalities by simple back-end integration on top of CMOS electronics.

In this work, a promising device for direct optical envelope mixing, the Intrinsic Photomixing Detector (IPD) based on hydrogenated amorphous silicon, is reported. The IPD directly generates a photocurrent proportional to the nonlinear mixing of two optical modulation envelope functions. Experiments illustrate efficient mixing in the visible range at low light levels down to ϕ1 = 4.36 mW/cm2 (444 nm) and ϕ2 = 1.03 mW/cm2 (636 nm). Modulation frequencies exceeding the MHz range are demonstrated. Electro-optical simulations identify defect-induced electrical field screening within the absorber to cause the nonlinear mixing process, opening-up the opportunity to tailor devices toward application-specific requirements. The IPD functionality paves the way toward very simple but high-performance photodetectors for 3D imaging and ranging for direct optical convolutional sensors or for efficient optical logic gates. Using amorphous silicon provides a photodetector material base, which can easily be integrated on top of silicon electronics, enabling fill factors of up to 100%.

In this work, we report on the bias-tunable and highly sensitive irradiance-dependent focus-induced photoresponse (FIP) in amorphous silicon p-i-n diodes for enhanced three-dimensional imaging applications. We identify a nonlinear current breakdown at irradiance down to at least $0.6\mu \mathrm{W}/\mathrm{m}{\mathrm{m}}^2$ due to defect-induced electrical field screening, surpassing state-of-the-art device sensitivities by at least a factor of 16 in the visible range. We further demonstrate the tunability of FIP by systematic device and field engineering to enable both precise and long-range high-resolution distance measurements in just one device architecture. We evaluate distance measurements up to at least 15 m and achieve a depth resolution of 2.1 mm at 3.3 m. The reproducible low-temperature (300 °C or lower) plasma-enhanced chemical vapor-deposition technology enables systematic tailoring of the FIP for three-dimensional imaging applications and allows for back-end sensor integration on top of silicon or flexible electronics with fill factors up to 100%.

The increasing demand for sustainable energy as a means to combat the impact of climate change is addressed via a novel concept in the present work. Herein presented are developed transferable encapsulated dye-sensitized solar cells, canonically “solar capsules”, for photovoltaic applications on alternative surfaces, such as facades. The solar capsule assembly houses all the components necessary for photovoltaic energy conversion, enclosed within a semiconductor nanotubular array, making them truly unique in their construction. This capsule-style unit enables an easy transfer and draft onto a wide range of materials and surfaces for photovoltaic functionalization and applications. This type of dye-sensitized solar cell typically consists of transferred solar capsules and two additional electrodes. The design and construction of solar capsules means they have a high economic viability as they can seamlessly be up-scaled using commercially established techniques such as anodization and subsequent functionalization. This work demonstrates a working model of such transferable solar capsules by fabricating TiO₂ nanotubes that are functionalized via facile dip- and spin-coating techniques in a wet lab at ambient conditions. These prototypes are characterized in bulk and are thoroughly investigated at the nanoscale for information on the chemical distribution of the constituents, as they may be influenced during the manufacturing process.

Current optical depth sensing technologies suffer from combining measurement performance with system simplicity and scalable integration at high pixel densities. The intrinsic photomixing detector (IPD) can overcome these issues and enables high precision time-of-flight depth sensing at visible and near-infrared wavelengths based on an electrical referenced nonlinear mixing process in amorphous semiconductors. First depth sensor prototypes demonstrate mixing efficiencies of up to 47%, a mean depth resolution of 5 mm at distances from 0 m to 2 m at 457 nm, and near-infrared detection capabilities down to 450 µW/cm ² at 785 nm. The IPD paves the way towards high-performance depth sensing at a simple, scalable, and CMOS-compatible integration platform with pixel fill factors up to 100%.

The increasing demand for sustainable energy as a means to combat the impact of climate change is addressed via a novel concept in the present work. Herein, the development of encapsulated dye-sensitized solar cells, canonically “solar capsules”, for photovoltaic applications on alternative surfaces, such as facades, is presented. The solar capsule assembly houses all components necessary for photovoltaic energy conversion, enclosed within a semiconductor nanotubular array, making them truly unique in their construction. This capsule-style unit enables an easy transfer and draft onto a wide range of materials and surfaces for photovoltaic functionalization and applications. This type of dye-sensitized solar cell typically consists of transferred solar capsules and two additional electrodes. The design and construction of solar capsules have high economic viability as they can seamlessly be up-scaled using commercially established techniques such as anodization and subsequent functionalization. This work demonstrates a working model of such a capsule by fabricating TiO2 nanotubes that are functionalized via facile dip- and spin-coating techniques in a wet lab at ambient conditions. These prototype solar capsules are characterized in bulk and are thoroughly investigated at the nanoscale for information on the chemical distribution of the constituents, as they may be influenced during the manufacturing process.