Wide‐Bandgap Perovskite Solar Cells With Large Open‐Circuit Voltage of 1653 mV Through Interfacial Engineering

Abstract

Low-cost wide-bandgap solar cells are attractive candidates for potential applications including tandem photovoltaics, solar-driven electrochemical energetic devices, and photovoltaic solar panels for spacecraft due to their relatively high output voltage and sustainability in critical environment. Recently, solar cells based on the organic-inorganic lead halide perovskites have emerged as a promising avenue toward high power conversion efficiency (PCE). However, the investigations on achieving high operating voltage with sufficient output power remains a missing part for the halide perovskite solar cells. Here the effectiveness of employing both anode and cathode interfacial modification layers to reach high open-circuit voltage (V OC ) for the methylammonium lead tribromide (MAPbBr 3 ) perovskite solar cells is demonstrated. Specifically, high work function e-beam processed MoO x layer with vacuum annealing treatment is used to reengineer the anode interface and an atomic layer deposited ZrO 2 layer is used to modify the cathode interface, respectively. The minimized energy barrier height by MoO x modification and hole-blocking effect by ZrO 2 synergistically restrain the charge carrier recombination loss and render a consequent larger quasi-Fermi level separation that endows a higher V OC . The MAPbBr 3 perovskite solar cell with a highest PCE of 10.08% and a new record V OC of 1653 mV under one sun-illumination are demonstrated.The organic-inorganic lead halide perovskite based photovoltaics have attracted huge attention in the past few years. [1][2][3][4][5] The unique electronic band structures, large dielectric constant, and relatively small effective masses make them optimal candidates for solar cell applications. [6][7][8][9][10] To date, vast research attentions have been driven to the classic prototype methylammonium lead triiodide (MAPbI 3 ) perovskite owning to its benign bandgap of 1.5-1.6 eV [11] that well matches the solar spectra. In contrast, solar cells based on wide-bandgap halide perovskite derivatives such as methylammonium lead tribromide (MAPbBr 3 ) have got less focus for its lower maximum efficiency predicted by Shockley-Queisser theory. [12] Nevertheless, the anticipated higher open-circuit voltage (V OC ) delivered by the wide-bandgap perovskite solar cells is expected to offer great opportunities for various applications including but not limited to solar driven water electrolysis, [13] electrocatalysis [14] and electrochemical energy storage, [15] multijunction solar cells, [16] space solar panels [17] and solar driving electronics for yellow and blue light emitting diode (LED). [18,19] To reach a high V OC and simultaneously maintain a large out-put power, most previous studies have focused on optimizing the perovskite polycrystalline film quality and synthesizing novel electrode buffer-layers. [20][21][22][23][24][25] The advances in techniques of growing high-quality perovskite thin films have revealed the superior electronic properties with carrier diffusion length in order of mi...

Conjugated Molecules “Bridge”: Functional Ligand toward Highly Efficient and Long‐Term Stable Perovskite Solar Cell

“…Theoretically, the open voltage of PSCs mainly depended on the splitting of electron and hole quasi‐Fermi levels in the fabricated devices . Previous studies have shown that as for the 2D–3D perovskite stacking‐layered architecture, large‐bandgap 2D perovskite capping layer could induce larger Fermi‐level separation, in favor of the enhanced open‐circuit voltage .…”

“…The energy disorder of the whole device was characterized to verify the theoretical analysis. The energy disorder is an explicit expression of the density of states (DOS) under a non‐equilibrium state that can be induced by external driving force . The DOS of electrons in the device can be achieved by the chemical capacitance ( C μ ) by means of impedance spectroscopy.…”

Inorganic CsPbI2Br Perovskite Solar Cells: The Progress and Perspective

“…Organic materials with such a deep highest occupied molecular orbital (HOMO) that match with the CsPbI 2 Br are easily oxidized by oxygen, leading to instable PSCs. Therefore, searching and synthesizing new inorganic HTL materials with appropriate energy levels are critical and important for high‐efficiency and high‐voltage CsPbI 2 Br PSCs …”

Choose Your Own Adventure: Fabrication of Monolithic All‐Perovskite Tandem Photovoltaics

“…[ 215 ] Indeed, the highest V OC obtained for MAPbBr 3 based devices used non‐traditional CLs, specifically NiO x /MoO x as the HTL and ZnO 2 /PCBM as the ETL. [ 214 ] Similarly, V OC gains for MAPbBr 3 based devices were obtained using both PEDOT:PSS with ICBA as well as TiO 2 with PIF8‐TAA. [ 29,117 ] Swapping spiro‐OMeTAD for PTB7 improved the V OC by 50 mV for CsPbI 3 QDs, reaching a % V OC‐SQ of 90%.…”

“…However, halide segregation does not explain why MAPbBr 3 often has a relatively low % V OC‐SQ , as do CsPbI 3 thin film devices. [ 102,214 ] Nor does this explain why wide‐ E g n–i–p devices have the highest % V OC‐SQ and not p–i–n ( Figure A). [ 99,114 ] In fact, recently it has been shown that the V OC loss expected from halide segregation is small, only around ≈70 mV which does not account for the majority of the large V OC losses, which can be ≈500 mV.…”