Organo-metal halide perovskite solar cells based on planar architecture have been reported to achieve remarkably high power conversion efficiency (PCE, >16%), rendering them highly competitive to the conventional silicon based solar cells. A thorough understanding of the role of each component in solar cells and their effects as a whole is still required for further improvement in PCE. In this work, the planar heterojunction-based perovskite solar cells were simulated with the program AMPS (analysis of microelectronic and photonic structures)-1D. Simulation results revealed a great dependence of PCE on the thickness and defect density of the perovskite layer. Meanwhile, parameters including the work function of the back contact as well as the hole mobility and acceptor density in hole transport materials were identified to significantly influence the performance of the device. Strikingly, an efficiency over 20% was obtained under the moderate simulation conditions.

A mesoporous SnO2electrode is firstly introduced in the CH3NH3PbI3perovskite solar cell as the electron-transporting material and scaffold layer with over 10% power conversion efficiency.

Compared to that of methylammonium lead iodide perovskite (MAPbI), formamidinium lead iodide perovskite (FAPbI) has a smaller energy band gap and greater potential efficiency. To prevent the transformation of α-FAPbI to δ-FAPbI, preparation of (FA)(MA)PbI was regarded as an effective route. Usually, the planar (FA)(MA)PbI perovskite solar cells are fabricated by a solution process. Herein, we report a low-pressure vapor-assisted solution process (LP-VASP) for the growth of (FA)(MA)PbI perovskite solar cells that features improved electron transportation, uniform morphology, high power conversion efficiency (PCE), and better crystal stability. In LP-VASP, the (FA)(MA)PbI films were formed by the reaction between the PbI film with FAI and MAI vapor in a very simple vacuum oven. LP-VASP is an inexpensive way to batch-process solar cells, avoiding the repeated deposition solution process for PbI films, and the device had a low cost. We demonstrate that, with an increase in the MAI content, the (101) peak position of FAPbI shifts toward the (110) peak position of MAPbI, the (FA)(MA)PbI perovskites are stable, and no decomposition or phase transition is observed after 14 days. The photovoltaic performance was effectively improved by the introduction of MA with the highest efficiency being 16.48% under conditions of 40 wt % MAI. The carrier lifetime of (FA)(MA)PbI perovskite films is approximately three times longer than that of pure FAPbI. Using this process, solar cells with a large area of 1.00 cm were fabricated with the PCE of 8.0%.

The thermal decompositions of pyrazine, pyrimidine, and pyridine in shock waves have been investigated using the complementary techniques of laser-schlieren (LS) densitometry and time-of-flight (TOF) mass spectrometry (1600−2300 K, 150−350 Torr). A free radical chain reaction with initiation by ring C−H fission in the pyrolyses of all three azines is proposed. The measured C−H fission rates are compared and analyzed by RRKM theory. Barriers of 103 ± 2 kcal/mol for pyrazine, 98 ± 2 for pyrimidine, and 105 ± 2 for pyridine have been determined, supporting values lower than the barrier for C−H fission in benzene, 112 kcal/mol. The lower barriers for the azines are explained by the additional contributions of resonance structures of azyl radicals due to neighboring N−C interactions, which serve to further stabilize the azyl radicals. Detailed chain mechanisms are constructed to model the LS profiles and the TOF concentration profiles of the major products, hydrogen cyanide, acetylene, cyanoacetylene, and diacetylene. Of particular interest are the TOF observations and the mechanistic explanation of temperature dependent maxima seen in the formation of cyanoacetylene in the presence or absence of excess H2.