Reduced Open‐Circuit Voltage Loss of Perovskite Solar Cells via Forming p/p⁺ Homojunction and Interface Electric Field on the Surfaces of Perovskite Film

Abstract

of methylammonium iodide (MAI) with formamidine iodide (FAI) improves the structure stability of perovskite crystal and maximizes the short-circuit current density (J sc ) of PVSCs due to the lower bandgap of FAPbI 3 perovskite film, which significantly enhances the device stability and efficiency. [9][10][11] Recently, many works focus on minimizing the interfacial nonradiative recombination and further improving the efficiency of PVSCs by introducing passivation layers since the defect states on the perovskite surface is much larger than that in the perovskite bulk film. [12][13][14] In addition to the improvement of efficiency, the passivation layers also improve the stability of PVSCs by protecting the functional layers from external water or oxygen erosion and retraining ions' migration inside the devices. [15][16][17] The synergetic development of composition engineering, additive engineering, and interface engineering facilitates the charge transportation and reduces nonradiative recombination in the device, which leads to the enhancement of certified PCE up to 25.5%. [4,18,19] However, this efficiency still lags behind the theoretical efficiency defined by the Shockley-Queisser theory due to the severe nonradiative recombination losses inside devices, thus strategies are still needed to be developed to suppress the nonradiative recombination losses and further improve the device efficiency, especially for the open-circuit voltage (V oc ) while the J sc and fill factor (FF) are approaching the theoretical limit. [20][21][22] The V oc of PVSC is determined by the internal quasi-Fermi level splitting (QFLS) in the absorber layer. [22] The QFLS will reduce compared with the QFLS of the neat perovskite film when the charge transport layers (CTLs) attach to the perovskite layer, which is possibly induced by the mismatched energy level alignment between different layers and the defects at the perovskite/CTL interfaces. [23] The reduction of QFLS should be minimized as possible for fabrication of high-performance PVSCs as it leads to the reduction of V oc and efficiency. Thus, it is urging to reduce nonradiative recombination losses aroused by defects and mismatched energy level alignment between the perovskite layer and the CTLs so as to reduce the V oc loss.Theoretical simulations and experimental data show that the perovskite materials possess self-doping characteristic by The severe nonradiative recombination losses limit the further improvement of open-circuit voltage (V oc ) and power conversion efficiency (PCE) of perovskite solar cells (PVSCs). In this work, the 4,4′-cyclohexylidenebis [N,N-bis(4-methylphenyl) benzene amine] is dissolved into the antisolvent to prepare perovskite films, which reduces defects, improves the crystallinity, and induces a p/p + homojunction on the top surface of perovskite film. Besides, the 2-thiophenemethylammonium iodide and 2-thiophenethylammonium iodide form interface electric field and passivate defects on the bottom surface of perovskite film. The p/p + homojunction and...

Synergetic effect of TiO2/ZnO bilayer photoanodes realizing exceptionally high VOC for dye-sensitized solar cells under outdoor and indoor illumination

“…3(C), to intersect the voltage axis. 41–44 The obtained V fb values for T + Z1, T + Z2, and T + Z3 are observed to be shifted towards more negative potentials compared to the standard T device (Table 1). This shift indicates that in the bilayer devices, specifically with the inclusion of a ZnO layer on top of the TiO 2 , the conduction band (CB) is shifted towards more negative potentials.…”

ETL-Free Perovskite Solar Cells with an Efficiency of 19.81% in Open Air

“…The hysteresis index (HI = (PCE reverse –PCE forward )/PCE reverse ) was calculated to be 0.026 and 0.073 for the devices with and without TiO 2 /C NFs additive, respectively. The significantly reduced hysteresis derived from efficient charge extraction and limited carrier nonradiative recombination . As displayed in Figure b, the histograms depict the PCE values of 40 highly efficient and reproducible PSCs.…”

Minimized Energy Loss at the Buried Interface of p‐i‐n Perovskite Solar Cells via Accelerating Charge Transfer and Forming p–n Homojunction

“…The µ hall of Poly-TPD films treated with CMD and AMD strategies increases to 0.139 and 0.343 cm 2 V −1 s −1 from 0.021 cm 2 V −1 s −1 of the pristine one. In addition, the n hall of PTAA films treated with CMD and AMD strategies increases [27,28] Adv. Energy Mater.…”