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Solar Cells Notes

Currently most solar cells are based on silicon and show efficiencies over 15% In the past few years the photovoltaic field has experienced a dramatic boost due to the development of perovskitebased solar cells (PSCs) They have outperformed established organic and hybrid materials already with an efficiency of 21% after only few years of investigation.

So what exactly are the perovskite solar cells In the narrow sense perovskite refers to the Calcium titanate which has a pseudocubic structure Right now perovskite refers to a class of compounds.

Which have the same type of crystal structure as calcium titanate For a typical perovskite used in solar cells A is methylammonium B is lead and X is halide usually chloride or iodide Since this is a relatively general structure.

You can pick any one item from columns a, b or X3 to come up with a valid name The table demonstrates how vast the parameter space is for potential material/structure combinations The choice of material combinations will be crucial for determining both the optical and electronic properties.

Next we focus on what great properties perovskite solar cells possess It has been agreed on that the organicinorganic hybrid nature is what makes it so successful The organic component A renders good solubility to the perovskite and facilitates selfassembly.

The inorganic component produces an extended network by covalent and ionic interactions rather than weaker forces such as Van der Waals force Such strong interaction allows for precise crystalline structure in the deposited films However, it is also this property that makes perovskite material sensitive to humidity Thus careful encapsulation is needed to prevent the solar cells from decomposition Around 2014, scientists observed the hysteretic currentvoltage behavior.

Of perovskite solar cells and this specific property can lead to an over or underestimation of the solar cell efficiency In provskite solar cells there is a discrepancy between forward scan and reverse scan Apart from scan direction this kind of discrepancy also depends on scan rate.

Light and voltage bias conditions and contact interface according to uger et al More and more results have recently supported the proposal that the hysteresis originates from ion movement within the perovskite layer But wait a minute Speaking of diffusion length there has been discussion about its concept.

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