This work investigates the effect of tantalum doping in compact TiO2 layer on the performance of planar spiro-OMeTAD free perovskite solar cells. 40% improvement in the overall efficiency was obtained as compared to the device with undoped TiO2.

Metal halide perovskites (MHPs) have recently emerged as an ideal semiconductor for photovoltaic application. Much of the advantageous properties of perovskite is dominated by its large charge carrier mobility (μ)...

Quasi-two-dimensional (2D) Ruddlesden–Popper (RP) perovskites are currently considered as the material of choice for the next-generation light-emitting diodes (LEDs) due to their superior optoelectronic properties. Despite their spectacular external quantum efficiency, the excessive surface defect states generated due to the reduced crystal size and phase impurity limit their radiative recombination efficiency. In the present work, we have shown the order of magnitude enhancement of radiative emission in butylamine (BA)-based quasi-2D perovskite (BA)2(MA) n−1Pb n Br3n+1 after passivating with two different Lewis basesa small organic molecule triphenylphosphine oxide (TPPO) and an insulating polymer polymethyl methacrylate (PMMA). The reduction in crystal grain size was observed after passivation, attributed to the complexation of the passivating molecules (PM) on the surface and nanocrystal pinning (A-NCP) phenomena. Both the steady-state and time-resolved photoluminescence study confirmed significant enhancement in fluorescence intensity and improved average lifetime (τavg. = 19.4 ns) after surface passivation. The interaction mechanism between the layered perovskite and PMs was probed with FTIR spectroscopy, XPS, and KPFM study. All these studies confirmed that the CO group in PMMA and PO group in TPPO deactivate the acceptor-type defects (uncoordinated Pb2+ and Br vacancies) in these RP perovskites. Furthermore, the stability of the passivated film enhanced significantly, as confirmed by contact angle measurement. Our study establishes that uncoordinated Pb2+ passivation by a Lewis base provides a viable strategy for photoluminescence (PL) lifetime, intensity, and stability enhancement in quasi-2D perovskite films.

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In this work, methylammonium lead tri-iodide perovskite has been synthesized by spin coating of lead acetate trihydrate and methylammonium iodide precursor on preheated substrate. Significant difference in film morphology has been observed as the temperature was varied from room temperature to 120 °C prior to spin coating. Nucleation and growth mechanism is revisited to find out the optimum substrate temperature for fabricating uniform perovskite films and is attributed to the fast homogeneous nucleation followed by delayed growth process. Electrochemical impedance spectroscopy measurement at the perovskite−liquid electrolyte interface reveals the impact of film morphology on the anomalous diffusion behavior observed at the low frequency regime.

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