Interfacial modification using the cross-linkable tannic acid for highly-efficient perovskite solar cells with excellent stability

Although the performance of perovskite solar cells(PSCs)has been dramatically increased in recent years,stability is still the main obstacle preventing the PSCs from being commercial.PSC device instability can be caused by a variety of reasons,including ions diffusion,surface and grain boundary defects,etc.In this work,the cross-linkable tannic acid(TA)is introduced to modify perovskite film through post-treatment method.The numerous organic functional groups(–OH and C=O)in TA can interact with the uncoordinated Pb^(2+)and I^(-)ions in perovskite,thus passivating defects and inhibiting ions diffusion.In addition,the formed TA network can absorb a small amount of the residual moisture inside the device to protect the perovskite layer.Furthermore,TA modification regulates the energy level of perovskite,and reduces interfacial charge recombination.Ultimately,following TA treatment,the device efficiency is increased significantly from 21.31%to 23.11%,with a decreased hysteresis effect.Notably,the treated device shows excellent air,thermal,and operational stability.In light of this,the readily available,inexpensive TA has the potential to operate as a multipurpose interfacial modifier to increase device efficiency while also enhancing device stability.

Evaluation of myocardial infarction patients after coronary revasculation by dual-phase multi-detector computed tomography:Now and in future

Multidetector-row computed tomography(MDCT) has become one of the major tools in diagnosing and evaluating patients with coronary artery disease in recent years.In selected patients,MDCT has been shown to provide more reliable accuracy in detection of stent patency than invasive coronary angiography.Chiou et al reported a delicate infarcted myocardium at-risk score.According to their results,the MDCT-based myocardium at-risk score had a good correlation with the thallium 201 ST-segment elevation myocardial infarction-based summed difference score(r = 0.841,P < 0.001).They claimed that dual-phase MDCT is useful in detecting different patterns of obstructive lesions and the extent of myocardium at risk.In this commentary,we discuss the current status of the clinical application of MDCT in patients with myocardial infarction in relation to evaluating the myocardial perfusion defect,detecting reversible myocardial ischemia,assessing myocardial viability,estimating target lesion restenosis,and calculating of fractional flow reserve from MDCT.

Anion-induced N-doping of naphthalenediimide polymer semiconductor in organic thin-film transistors

Molecular doping is an important strategy to improve the charge transport properties of organic semiconductors in various electronic devices.Compared to p-type dopants,the development of n-type dopants is especially challenging due to poor dopant stability against atmospheric conditions.In this article,we report the n-doping of the milestone naphthalenediimide-based conjugated polymer P(NDI2OD-T2)in organic thin film transistor devices by soluble anion dopants.The addition of the dopants resulted in the formation of stable radical anions in thin films,as confirmed by EPR spectroscopy.By tuning the dopant concentration via simple solution mixing,the transistor parameters could be readily controlled.Hence the contact resistance between the electrodes and the semiconducting polymer could be significantly reduced,which resulted in the transistor behaviour approaching the desirable gate voltage-independent model.Reduced hysteresis was also observed,thanks to the trap filling by the dopant.Under optimal doping concentrations the channel on-current was increased several fold whilst the on/off ratio was simultaneously increased by around one order of magnitude.Hence doping with soluble organic salts appears to be a promising route to improve the charge transport properties of n-type organic semiconductors.