Fully spray-coated triple-cation perovskite solar cells

We use ultrasonic spray-coating to sequentially deposit thin films of tin oxide, a triple-cation perovskite and spiro-OMeTAD, allowing us fabricate perovskite solar cells (PSCs) with a champion reverse scan power conversion efficiency (PCE) of 19.4% on small-area substrates. We show that the use of spray-deposition permits us to rapidly (>80 mm s−1) coat 25 mm × 75 mm substrates that were divided into a series of devices each with an active area of 15.4 mm2, yielding an average PCE of 10.3% and a peak PCE of 16.3%. By connecting seven 15.4 mm2 devices in parallel on a single substrate, we create a device having an effective active area of 1.08 cm2 and a PCE of 12.7%. This work demonstrates the possibility for spray-coating to fabricate high efficiency and low-cost perovskite solar cells at speed

What works for wellbeing in culture and sport? Report of a DELPHI process to support coproduction and establish principles and parameters of an evidence review

Aims: There is a growing recognition of the ways in which culture and sport can contribute to wellbeing. A strong evidence base is needed to support innovative service development and a 3-year research programme is being undertaken to capture best evidence of wellbeing impacts and outcomes of cultural and sporting activities in order to inform UK policy and practice. This article provides an overview of methods and findings from an initial coproduction process with key stakeholders that sought to explore and agree principles and parameters of the evidence review for culture, sport and wellbeing (CSW). Methods: A two-stage DELPHI process was conducted with a purposeful sample of 57 stakeholders between August and December 2015. Participants were drawn from a range of culture and sport organisations and included commissioners and managers, policy makers, representatives of service delivery organisations (SDOs) and scholars. The DELPHI 1 questionnaire was developed from extensive consultation in July and August 2015. It explored definitions of wellbeing, the role of evidence, quality assessment, and the culture and sport populations, settings and interventions that are most likely to deliver wellbeing outcomes. Following further consultation, the results, presented as a series of ranked statements, were sent back to participants (DELPHI 2), which allowed them to reflect on and, if they wished, express agreement or disagreement with the emerging consensus. Results: A total of 40 stakeholders (70.02%) responded to the DELPHI questionnaires. DELPHI 1 mapped areas of agreement and disagreement, confirmed in DELPHI 2. The exercise drew together the key priorities for the CSW evidence review. Conclusion: The DELPHI process, in combination with face-to-face deliberation, enabled stakeholders to engage in complex discussion and express nuanced priorities while also allowing the group to come to an overall consensus and agree outcomes. The results will inform the CSW evidence review programme until its completion in March 2018

Direct measurement of the exciton binding energy and effective masses for charge carriers in organic–inorganic tri-halide perovskites

Solar cells based on the organic-inorganic tri-halide perovskite family of materials have shown remarkable progress recently, offering the prospect of low-cost solar energy from devices that are very simple to process. Fundamental to understanding the operation of these devices is the exciton binding energy, which has proved both difficult to measure directly and controversial. We demonstrate that by using very high magnetic fields it is possible to make an accurate and direct spectroscopic measurement of the exciton binding energy, which we find to be only 16 meV at low temperatures, over three times smaller than has been previously assumed. In the room temperature phase we show that the binding energy falls to even smaller values of only a few millielectronvolts, which explains their excellent device performance due to spontaneous free carrier generation following light absorption. Additionally, we determine the excitonic reduced effective mass to be 0.104me (where me is the electron mass), significantly smaller than previously estimated experimentally but in good agreement with recent calculations. Our work provides crucial information about the photophysics of these materials, which will in turn allow improved optoelectronic device operation and better understanding of their electronic properties

Highly efficient and stable inverted perovskite solar cell employing PEDOT:GO composite layer as a hole transport layer

The beneficial use of a hole transport layer (HTL) as a substitution for poly(3,4-ethlyenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is regarded as one of the most important approaches for improving the stability and efficiency of inverted perovskite solar cells. Here, we demonstrate highly efficient and stable inverted perovskite solar cells by applying a GO-doped PEDOT:PSS (PEDOT:GO) film as an HTL. The high performance of this solar cell stems from the excellent optical and electrical properties of the PEDOT:GO film, including a higher electrical conductivity, a higher work function related to the reduced contact barrier between the perovskite layer and the PEDOT:GO layer, enhanced crystallinity of the perovskite crystal, and suppressed leakage current. Moreover, the device with the PEDOT:GO layer showed excellent long-term stability in ambient air conditions. Thus, the enhancement in the efficiency and the excellent stability of inverted perovskite solar cells are promising for the eventual commercialization of perovskite optoelectronic devices