Monovalent Copper Cation Doping Enables High-Performance CsPbIBr2-Based All-Inorganic Perovskite Solar Cells

Abstract

Organic–inorganic perovskite solar cells (PSCs) have delivered the highest power conversion efficiency (PCE) of 25.7% currently, but they are unfortunately limited by several key issues, such as inferior humid and thermal stability, significantly retarding their widespread application. To tackle the instability issue, all-inorganic PSCs have attracted increasing interest due to superior structural, humid and high-temperature stability to their organic–inorganic counterparts. Nevertheless, all-inorganic PSCs with typical CsPbIBr2 perovskite as light absorbers suffer from much inferior PCEs to those of organic–inorganic PSCs. Functional doping is regarded as a simple and useful strategy to improve the PCEs of CsPbIBr2-based all-inorganic PSCs. Herein, we report a monovalent copper cation (Cu+)-doping strategy to boost the performance of CsPbIBr2-based PSCs by increasing the grain sizes and improving the CsPbIBr2 film quality, reducing the defect density, inhibiting the carrier recombination and constructing proper energy level alignment. Consequently, the device with optimized Cu+-doping concentration generates a much better PCE of 9.11% than the pristine cell (7.24%). Moreover, the Cu+ doping also remarkably enhances the humid and thermal durability of CsPbIBr2-based PSCs with suppressed hysteresis. The current study provides a simple and useful strategy to enhance the PCE and the durability of CsPbIBr2-based PSCs, which can promote the practical application of perovskite photovoltaics.

Lead‐Free All‐Inorganic Cesium Bismuth Iodide‐Based Perovskite Solar Cells: Recent Advances, Current Limitations, and Future Prospects

“…[ 23,30,31 ] Nevertheless, several crucial problems still existed such as the toxicity of Pb and hygroscopicity of organic A‐site cations, severely hampering the commercialization of PSCs. [ 32–34 ]…”

Impact of Cr doping on the structural and optoelectronic properties of a CsPbIBr2 perovskite solar cell

“…This leads to the enhancement of both the PCE and the long-term stability of perovskite solar cells. [13][14][15][16] A device with an outstanding power conversion efficiency (PCE) of 11.33% and an open-circuit voltage (V OC ) of 1.26 V was created by Liang et al using a two-stage sequential deposition process to create films of CsPb 0.9 Sn 0.1 IBr 2 . In order to enhance the performance of perovskite solar cells, Li et al raised the Sn 2+ content and created CsPb 0.75 Sn 0.25 IBr 2 using a conventional one-step antisolvent processing method.…”

Additive Engineering for Mixed Lead–Tin Narrow-Band-Gap Perovskite Solar Cells: Recent Advances and Perspectives

“…The new third-generation solar cells, such as perovskite solar cells (PSCs), dye-sensitized solar cells, and quantum dot solar cells, have received increasing interests recently as a result of the facile fabrication process, low-cost raw material, and superior theoretical PCEs. − In particular, PSCs with lead (Pb)-based halide perovskites as light absorbers exhibit several unique and excellent optical/electronic properties, including adjustable band gaps, high optical absorption coefficients, high mobility, and long diffusion length of charge carriers, leading to a rapid boosting rate of PCEs of PSCs from 3.8 to 25.7% in the last 14 years. − Therefore, the newly developed PSCs are considered as the most potential replacements to traditional silicon-based solar cells for large-scale and sustainable photovoltaic power generation. , Although the PCEs of Pb-based PSCs have reached 25.7% recently, the large-scale applications of Pb-based organic–inorganic hybrid PSCs still face many crucial challenges. − First, the band gaps of Pb-based organic–inorganic perovskites currently used in high-performance PSCs are generally 1.5–1.6 eV, which are much larger than the theoretical optimal band gap of 1.3–1.4 eV for solar cells calculated according to the Shockley–Queisser (S–Q) theory . Second, the toxicity of Pb is extremely harmful to the environment and humans. − To overcome these problems, numerous researchers are trying to develop new Pb-free or Pb-less halide perovskites using non-toxic metals, including tin (Sn), bismuth (Bi), and germanium (Ge), to achieve sustainable and clean perovskite photovoltaics. − Among various alternatives to Pb 2+ cations, Sn 2+ cations have similar electronic structures to Pb 2+ and comparable ion radii (the ionic radii of Sn 2+ and Pb 2+ are 110 and 119 pm, respectively). − Therefore, partial or complete replacement of Pb 2+ in perovskites by Sn 2+ will not lead to significant lattice distortions in the perovskite structure .…”