Quantifying the Energy Losses in CsPbI₂Br Perovskite Solar Cells with an Open-Circuit Voltage of up to 1.45 V

Abstract

CsPbI 2 Br perovskite solar cells (PSCs) have attracted much interest because of their thermodynamic stability, relatively stable cubic perovskite phase, and their potential as a top cell for tandem applications.However, the open-circuit voltage (V OC ) reported to date is in most cases well below the detailed balance (DB) limit for single-junction PSCs. Here, we demonstrate that adding lead acetate to the CsPbI 2 Br precursor allows us to substantially reduce losses due to nonradiative recombination. Corresponding champion devices reach a power conversion efficiency (η) of 16.7% and a highest V OC value of 1.45 V, which represents 90% of the DB limit for singlejunction PSCs at a bandgap of 1.89 eV. In order to disentangle the nonradiative recombination loss mechanisms, we quantify the origin of energy losses by calculating the radiative limit of the open-circuit voltage (V OC rad ) and the quasi-Fermi level splitting (QFLS) of perovskite films with and without other functional layers. We further analyze the strategies to reduce the residual losses in order to push the efficiency beyond the 90% theoretical limit.

Constructing D-π-A Type Polymers as Dopant-Free Hole Transport Materials for High-Performance CsPbI2Br Perovskite Solar Cells

“…The integrated current density of PE61-, PBDB-T-, and J52-based devices are 13.80, 12.87, and 13.62 mA cm –2 , respectively. There are decreases of EQE curves in the long wavelength, which can be ascribed to the insufficient absorption of CsPbI 2 Br, and this part of the long wavelength is absorbed by HTMs . The stabilized outputs at the maximum power point (MPP) of the PE61 device (Figure c) shows a stable PCE of 16.09% (at 1.15 V), while PBDB-T and J52 devices show a stable PCE of 14.76% (at 1.13 V) and a stable PCE of 14.92% (at 1.08 V), respectively.…”

“…There are decreases of EQE curves in the long wavelength, which can be ascribed to the insufficient absorption of CsPbI 2 Br, and this part of the long wavelength is absorbed by HTMs. 46 The stabilized outputs at the maximum power point (MPP) of the PE61 device (Figure 4c) shows a stable PCE of 16.09% (at 1.15 V), while PBDB-T and J52 devices show a stable PCE of 14.76% (at 1.13 V) and a stable PCE of 14.92% (at 1.08 V), respectively. The PE61 device also exhibits superior power output stability to PBDB-T and J52 devices, continuous to 1000 s. Then, the transient photocurrent (TPC) and transient photovoltage (TPV) measurements were performed to analyze the charge carrier dynamic in different devices.…”

Enhanced Interstitial Oxygen-Enabled Efficient CuAl(M)O2 Hole Extractors for Air-Stable All-Inorganic Perovskite Solar Cells

“…Through ion doping engineering, the E VB of CuAlO 2 moves down due to the increase of the hole concentration near the valence band (i.e., the increase of oxygen vacancies), which is consistent with the improvement of interstitial oxygen obtained by the XPS characterization. The down-shift of E VB of CuAl­(M)­O 2 minimizes its level mismatching degree with CsPbBr 3 , which favors the hole transfer and reduces the energy loss . Combining with the optical band gaps (Figure S8f), the minimum conduction band energy level ( E CB ) of CuAl­(M)­O 2 is calculated and shown in Figure c.…”

“…The down-shift of E VB of CuAl(M)O 2 minimizes its level mismatching degree with CsPbBr 3 , which favors the hole transfer and reduces the energy loss. 44 Combining with the optical band gaps (Figure S8f), the minimum conduction band energy level (E CB ) of CuAl(M)O 2 is calculated and shown in Figure 2c. The higher E CB of CuAl(M)O 2 than that of CsPbBr 3 can effectively block the reverse flow of the photogenerated electrons to restrain charge recombination, leading to a high-current and high-voltage output.…”

Cubic CsPbI3 Nanoarchitectonics with High and Stable Photoluminescence toward White Light-Emitting Diodes

“…These structural characteristics make the CsPbI 3 NCs easily change from a metastable black phase (γ) to a stable yellow phase (δ) under environmental conditions. To obtain high luminescent and stable CsPbI 3 NCs, a series of efforts have been devoted in the past few years, including replacing Pb ions with transition metals, to increase the formation energy, , while replacing Pb ions with smaller ions to increase the defect tolerance. − However, ion doping inevitably introduces a new emission center into perovskite NCs, which affects the color purity of the subsequently prepared light-emitting device. , Several teams have improved the stability of nanocrystals by treating them at higher temperatures to increase crystallinity, but this method requires higher temperatures to a great expense. A ligand modification strategy was considered to be an effective method to improve the stability of NCs.…”