Fundamental Efficiency Limit of Lead Iodide Perovskite Solar Cells

Abstract

Lead halide materials have seen a recent surge of interest from the photovoltaics community following the observation of surprisingly high photovoltaic performance, with optoelectronic properties similar to GaAs. This begs the question: What is the limit for the efficiency of these materials? It has been known that under 1-sun illumination the efficiency limit of crystalline silicon is ∼29%, despite the Shockley-Queisser (SQ) limit for its bandgap being ∼33%: the discrepancy is due to strong Auger recombination. In this article, we show that methyl ammonium lead iodide (MAPbI) likewise has a larger than expected Auger coefficient. Auger nonradiative recombination decreases the theoretical external luminescence efficiency to ∼95% at open-circuit conditions. The Auger penalty is much reduced at the operating point where the carrier density is less, producing an oddly high fill factor of ∼90.4%. This compensates the Auger penalty and leads to a power conversion efficiency of 30.5%, close to ideal for the MAPbI bandgap.

Light Absorption and Recycling in Hybrid Metal Halide Perovskite Photovoltaic Devices

“…This is contrary to what we observe in the Urbach energy, where E u decreases as the thickness of the perovskite thin film increase in the devices (Figure S3, Supporting Information). A decrease in E u typically results in a higher V oc as the density of tail states decreases . The drop in V oc in regime B is therefore most likely due the reduction in steady‐state carrier density, as the thickness of absorber material increases, as explained by Brendal and Queisser .…”

Recent Progresses on Defect Passivation toward Efficient Perovskite Solar Cells

“…In view of the simple processability of perovskite halides, one could expect non‐negligible defects at grain boundary and interface caused by low temperature processing. The presence of these defects leads to a decrease in crystal quality, and the energy band misalignment between the active layer with respect to the charge transport layer, thus seriously affecting charge carrier transportation, which could be one of the most important reasons for approaching its theoretical efficiency limit of 30.5% …”

Relation between Fluorescence Quantum Yield and Open‐Circuit Voltage in Complete Perovskite Solar Cells

“…It has been proposed by several authors that to present a maximized V oc , a solar cell with a given design should re‐emit all the incident photons absorbed by its active layer. This was initially proposed by Shockley and Queisser on the basis of detailed balance calculations (that are now widely used for the estimation of the maximum achievable PCE and other photovoltaic parameters such as V oc ) and by Ross on the basis of simple thermodynamic considerations .…”

“…This was initially proposed by Shockley and Queisser on the basis of detailed balance calculations (that are now widely used for the estimation of the maximum achievable PCE and other photovoltaic parameters such as V oc ) and by Ross on the basis of simple thermodynamic considerations . Their approaches led to the relation described by Equation , which predicts that V oc increases with the cell's external fluorescence quantum yield (QY). QY is the ratio of the number of photons re‐emitted by the active layer and escaping the cell to the number of incident photons absorbed by the active layer.…”