In this paper, an electron donor-acceptor (D-A) substituted dipolar chromophore (BTPA-TCNE) is developed to serve as an efficient dopant-free hole-transporting material (HTM) for perovskite solar cells (PVSCs). BTPA-TCNE is synthesized via a simple reaction between a triphenylamine-based Michler's base and tetracyanoethylene. This chromophore possesses a zwitterionic resonance structure in the ground state, as evidenced by X-ray crystallography and transient absorption spectroscopies. Moreover, BTPA-TCNE shows an antiparallel molecular packing (i.e., centrosymmetric dimers) in its crystalline state, which cancels out its overall molecular dipole moment to facilitate charge transport. As a result, BTPA-TCNE can be employed as an effective dopant-free HTM to realize an efficient (PCE ≈ 17.0%) PVSC in the conventional n-i-p configuration, outperforming the control device with doped spiro-OMeTAD HTM.

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Currently,the performance improvement for inverted perovskite solar cells (PVSCs) is mainly limited by the high open circuit voltage (V OC)l oss caused by detrimental nonradiative recombination (NRR) processes.H erein, we report as imple and efficient wayt os imultaneously reduce the NRR processes inside perovskites and at the interface by rationally designing an ew pyridine-based polymer hole-transporting material (HTM), PPY2,w hiche xhibits suitable energy levels with perovskites,high hole mobility,effective passivation of the uncoordinated Pb 2+ and iodide defects,aswell as the capability of promoting the formation of high-quality polycrystalline perovskite films.I na bsence of any dopants,t he inverted PVSCs using PPY2 as the HTM deliver an encouraging PCE up to 22.41 %w ith as mall V OC loss (0.40 V), among the best device performances for inverted PVSCs reported so far. Furthermore, PPY2-based unencapsulated devices showa n excellent long-term photostability,a nd over 97 %o fits initial PCE can be maintained after one sun constant illumination for 500 h.

To develop sensitive and selective CNchemosensors, a new imidazole-functionalized polyfluorene (P1) was designed and obtained conveniently, the fluorescence of which could be completely quenched by Cu 2+ ions at the concentration as low as 0.20 ppm in diluted solutions. By utilizing the much higher stability constant of the complex of CNand Cu 2+ , the quenched fluorescence of the solution of P1 by Cu 2+ ions could recover upon the addition of trace CNanions, with the detection limit down to 0.31 ppm, making P1 a novel, sensitive and selective cyanide probe.