24.04.15 KB. OK to add published OA paper to spira

Perovskites with bandgaps between 1.7 and 1.8 eV are optimal for tandem configurations with crystalline silicon (c-Si) because they facilitate efficient harvest of solar energy. In that respect, achieving a high open-circuit voltage (V OC ) in such wide-bandgap perovskite solar cells is crucial for a high overall power conversion efficiency (PCE). Here, we provide key insights into the factors affecting the V OC in wide-bandgap perovskite solar cells. We show that the influence of the hole transport layer (HTL) on V OC is not simply through its ionization potential but mainly through the quality of the perovskite−HTL interface. With effective interface passivation, we demonstrate perovskite solar cells with a bandgap of 1.72 eV that exhibit a V OC of 1.22 V. Furthermore, by combining the high-V OC perovskite solar cell with a c-Si solar cell, we demonstrate a perovskite−Si four-terminal tandem solar cell with a PCE of 27.1%, exceeding the record PCE of single-junction Si solar cells.

Here we report the investigation of controlled PbI2 secondary phase formation in CH3NH3PbI3 (MAPI) photovoltaics through post-deposition thermal annealing, highlighting the beneficial role of PbI2 on device performance. Using high-resolution transmission electron microscopy we show the location of PbI2 within the active layer and propose a nucleation and growth mechanism. We discover that during the annealing that PbI2 forms mainly in the grain boundary regions of the MAPI films and that at certain temperatures the PbI2 formed can be highly beneficial to device performance – reducing current–voltage hysteresis and increasing the power conversion efficiency. Our analysis shows that the MAPI grain boundaries as susceptible areas that, under thermal loading, initiate the conversion of MAPI into PbI2

Careful interface design and engineering are “keys” to effectively implement a conformal 10 nm plasma-assisted atomic-layer-deposited NiO film as hole transport layer in a p–i–n perovskite solar cell architecture.

Keywords: Schottky diode, radio frequency diodes, RFID, nanogap electrode, 13.56 MHz Main TextRadio Frequency Identification (RFID) is a rapidly growing technology used for wireless communication and the identification of objects in close proximity through radio waves. [1] Although already a billion dollar industry [2] , RFID technology promises substantial further growth by adopting fully printable processing routes. However, there remain several bottlenecks to be overcome before this opportunity can be realised, particularly pertaining to the high frequency performance of printable electronics.RFID tags are generally composed of a coupling element, or antenna, a direct current (DC) rectifier and integrated circuitry (IC). The rectifying element is by far the most important component in terms of high-frequency (HF) operation, as the logic may take place at much J. Semple et al., Small (2016), DOI: 10.1002/smll.201503110 2 lower frequencies than the RF base carrier frequency. Different frequency bands exist for different applications, though the current target for printable RFID is the widely employed 13.56 MHz band. [1] Conventionally, complementary metal-oxide-semiconductor (CMOS) technology favours the use of diode-connected metal-oxide-semiconductor field-effect transistors (MOSFETs) for rectification within this element. However, Schottky diodes, with their inherently lower voltage operation, lower series resistance and exponential currentvoltage relationship offer a superior choice for rectifiers. [4] There has been extensive work carried out in recent years to develop high frequency organic Schottky diodes following the pioneering work of Steudel et al. who demonstrated pentacene-based Schottky diode rectifiers operating at 50 MHz. [5] More recently C60-basedSchottky diodes with a cut-off frequency (fCO) up to 0.7 GHz have also been reported. [6] Diodes based on metal oxide materials (particularly In-Ga-Zn-O) have recently emerged as a promising material, demonstrating device performance up to and above 1 GHz. [7][8][9] Despite such promising results, manufacturing of these conventional staggered diodes relies on vacuum processing, which renders them incompatible with cost-effective large-volume product integration. To address this important bottleneck, recent work has been devoted to solutionprocessable organic diodes with adequate performance. [10][11][12] Si nanoparticles have recently been demonstrated as a potential route to solution processed diodes with cut-off frequencies as high as 1.6 GHz.[13] However, demonstrating high yield manufacturing of solution-processed diodes with cut-off frequency 50 MHz still remains a significant challenge.The operational frequency of Schottky diodes is inversely proportional to the product of the series resistance (RS) and junction capacitance (Cj). A common approach to boosting the device cut-off frequency is by reducing RS through the use of a high charge carrier mobility J. Semple et al., Small (2016) However, there are inherent problems with implementing...

Backbone functionalisation of conjugated polymers is crucial to their performance in many applications, from electronic displays to nanoparticle biosensors, yet there are limited approaches to introduce functionality. To address this challenge we have developed a method for the direct modification of the aromatic backbone of a conjugated polymer, post-polymerisation. This is achieved via a quantitative nucleophilic aromatic substitution (SNAr) reaction on a range of fluorinated electron-deficient comonomers. The method allows for facile tuning of the physical and optoelectronic properties within a batch of consistent molecular weight and dispersity. It also enables the introduction of multiple different functional groups onto the polymer backbone in a controlled manner. To demonstrate the versatility of this reaction, we designed and synthesised a range of emissive poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT)-based polymers for the creation of mono and multifunctional semiconducting polymer nanoparticles (SPNs) capable of two orthogonal bioconjugation reactions on the same surface.

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