HIGHLY EFFICIENT HOLE CONDUCTOR FREE PEROVSKITE BASED SOLAR CELLS

Perovskite is a promising light harvester for use in photovoltaic solar cells. In recent years, the power conversion efficiency of perovskite solar cells has been dramatically increased, making them a competitive source of renewable energy.

This work will discuss several topics related to perovskite based solar cells:

Micron sized grains in planar hole conductor free perovskite based solar cells, In this work we demonstrate the planar configuration on HTM free perovskite based solar cells. The CH₃NH₃PbI₃ perovskite was deposited using the spray technique to achieve micron size perovskite crystals. The number of spray passes changes the CH₃NH₃PbI₃ film thickness; 10 spray passes achieved a film thickness of 3.4m. Surprisingly, power conversion efficiency of 6.9% was demonstrated for this novel, simple solar cell structure with thick perovskite film that has no HTM. Capacitance-voltage measurements reveal charge accumulation at the CH₃NH₃PbI₃/Au interface while the compact TiO₂/CH₃NH₃PbI₃ junction showed a space charge region, which inhibits the recombination.

High Voltage hole conductor free perovksite solar cells.

In this work we demonstrate high open circuit voltage of 1.35V using Al₂O₃/CH₃NH₃PbBr₃ perovskite solar cells without a hole conductor. The CPD under light measured by SPV for CH₃NH₃PbBr₃ was more than twice than that for CH₃NH₃PbI₃, which results with smaller surface potential for the Al₂O₃/CH₃NH₃PbBr₃ cells. IMPS shows a longer recombination lifetime for the Al₂O₃/CH₃NH₃PbBr₃ cells than for the TiO₂/CH₃NH₃PbI₃ cells or for the TiO₂/CH₃NH₃PbBr₃ cells, further supporting the high open circuit voltage. The possibility to gain high open circuit voltage even without a hole transport material in perovskite solar cells shows that the perovskite/metal oxide interface has a major effect on the open circuit voltage in perovskite based solar cells.