The evolution of real-time medical diagnostic tools such as angiography and computer tomography from radiography based on photographic plates was enabled by the development of integrated solid-state X-ray photon detectors, based on conventional solid-state semiconductors. Recently, for optoelectronic devices operating in the visible and near infrared spectral regions, solution-processed organic and inorganic semiconductors have also attracted immense attention. Here we demonstrate a possibility to use such inexpensive semiconductors for sensitive detection of X-ray photons by direct photon-to-current conversion. In particular, methylammonium lead iodide perovskite (CH 3 NH 3 PbI 3 ) offers a compelling combination of fast photoresponse and a high absorption cross-section for X-rays, owing to the heavy Pb and I atoms. Solution processed photodiodes as well as photoconductors are presented, exhibiting high values of X-ray sensitivity (up to 25 µC mGy air -1 cm -3 ) and responsivity (1.9×10 4 carriers/photon), which are commensurate with those obtained by the current solid-state technology.

Solution processed organic solar cells based on blends of semiconducting polymers and soluble fullerene derivatives are showing impressive advances in photovoltaic power conversion efficiency, with recent reports of efficiencies in excess of 6%.[1]One of the key remaining factors limiting the performance of such blend or 'bulk heterojunction' solar cells is that they generally exhibit relatively modest voltage outputs, with the energy corresponding to the open circuit voltage, V OC , typically being less than half the optical gap. This V OC has been shown to be correlated to the energy levels of the donor and acceptor materials of the bulk heterojunction (BHJ). [2] In this paper, we compare the V OC of BHJ fabricated from four

In this work, we report efficient semitransparent perovskite solar cells using solution-processed silver nanowires (AgNWs) as top electrodes. A thin layer of zinc oxide nanoparticles is introduced beneath the AgNWs, which fulfills two essential functionalities: it ensures ohmic contact between the PC 60 BM and the AgNWs and it serves as a physical foundation that enables the solution-deposition of AgNWs without causing damage to the underlying perovskite. The as-fabricated semitransparent perovskite cells show a high fill factor of 66.8%, V oc = 0.964 V, J sc = 13.18 mA cm −2 , yielding an overall efficiency of 8.49% which corresponds to 80% of the reference devices with reflective opaque electrodes.Inorganic-organic halide perovskite solar cells have recently emerged as a promising photovoltaic technology due to their high efficiencies and low-cost processing potential. [1][2][3][4] The exceptional optoelectronic properties of the perovskite crystals such as high carrier mobility and long charge diffusion length promise highly efficient charge separation. 5,6 These intriguing characteristics make perovskites ideal materials for photovoltaic applications. Since the first device demonstration in 2009, power conversion efficiency (PCE) of perovskite solar cells processed by both vacuum-deposition and solutionprocessing has surged to over 15%. 2,4,[7][8][9] The continuous and fast progress in the research related to perovskite solar devices has established them as a serious contestant to the traditional silicon-based panels.Together with the considerable efforts devoted to pursuing high efficiencies via improved crystallization of perovskite and searching for low-cost interface materials, 4,10-13 aesthetic semitransparent perovskite solar cells have been simultaneously receiving growing attention because of their specific application in transparent architectures, 14-17 such as windows, rooftops, greenhouses and other fashion elements. To achieve efficient semitransparent perovskite devices, both the anode and the cathode of the devices should be highly transparent and conductive in order to minimize the optical and resistance losses. To date, several studies have reported semitransparent perovskite solar cells, but most of these devices employed thin metal films (Al, Ag, Au) as top electrodes which were fabricated based on energy-intensive evaporation processes. [15][16][17] It is well known that, in addition to low-cost materials, the cost reduction of photovoltaic devices substantially depends on the ability to use high-throughput coating techniques in combination with roll-to-roll processing. 18 Despite its importance, however, less attention has been paid to the exploration of solution-processable transparent electrodes for perovskite solar cells. Carbon based materials have received much attention for use as conducting electrodes for perovskite solar cells, due to their low-cost and high stability. 14,19,20 For example, Li et al.have recently reported semitransparent perovskite solar cells using carbon nanotub...

We developed a new method to accurately extract the singlet exciton diffusion length in organic semiconductors by blending them with a low concentration of methanofullerene[6,6]-phenyl-C 61butyric acid methyl ester (PCBM). The dependence of photoluminescence (PL) decay time on the fullerene concentration provides information on both exciton diffusion and the nanocomposition of the blend. Experimentally measured PL decays of blends based on two narrow band gap dithiophenebenzothiadiazole polymers, C-PCPDTBT and Si-PCPDTBT, were modeled using a Monte Carlo simulation of 3D exciton diffusion in the blend. The simulation software is available for download. The extracted exciton diffusion length is 10.5 AE 1 nm in both narrow band gap polymers, being considerably longer than the 5.4 AE 0.7 nm that was measured with the same technique in the model compound poly(3-hexylthiophene) as a reference. Our approach is simple, fast and allows us to systematically measure and compare exciton diffusion length in a large number of compounds.

Carbon bridged (C‐PCPDTBT) and silicon‐bridged (Si‐PCPDTBT) dithiophene donor–acceptor copolymers belong to a promising class of low bandgap materials. Their higher field‐effect mobility, as high as 10−2 cm2 V−1 s−1 in pristine films, and their more balanced charge transport in blends with fullerenes make silicon‐bridged materials better candidates for use in photovoltaic devices. Striking morphological changes are observed in polymer:fullerene bulk heterojunctions upon the substitution of the bridging atom. XRD investigation indicates increased π–π stacking in Si‐PCPDTBT compared to the carbon‐bridged analogue. The fluorescence of this polymer and that of its counterpart C‐PCPDTBT indicates that the higher photogeneration achieved in Si‐PCPDTBT:fullerene films (with either [C60]PCBM or [C70]PCBM) can be correlated to the inactivation of a charge‐transfer complex and to a favorable length of the donor–acceptor phase separation. TEM studies of Si‐PCPDTBT:fullerene blended films suggest the formation of an interpenetrating network whose phase distribution is comparable to the one achieved in C‐PCPDTBT:fullerene using 1,8‐octanedithiol as an additive. In order to achieve a balanced hole and electron transport, Si‐PCPDTBT requires a lower fullerene content (between 50 to 60 wt%) than C‐PCPDTBT (more than 70 wt%). The Si‐PCPDTBT:[C70]PCBM OBHJ solar cells deliver power conversion efficiencies of over 5%.