A Liquid Junction Photoelectrochemical Solar Cell Based on p-Type MeNH₃PbI₃ Perovskite with 1.05 V Open-Circuit Photovoltage

Abstract

A liquid junction photoelectrochemical (PEC) solar cell based on p-type methylammonium lead iodide (p-MeNH3PbI3) perovskite with a large open-circuit voltage is developed. MeNH3PbI3 perovskite is readily soluble or decomposed in many common solvents. However, the solvent dichloromethane (CH2Cl2) can be employed to form stable liquid junctions. These were characterized with photoelectrochemical cells with several redox couples, including I3(-)/I(-), Fc/Fc(+), DMFc/DMFc(+), and BQ/BQ(•-) (where Fc is ferrocene, DMFc is decamethylferrocene, BQ is benzoquinone) in CH2Cl2. The solution-processed MeNH3PbI3 shows cathodic photocurrents and hence p-type behavior. The difference between the photocurrent onset potential and the standard potential for BQ/BQ(•-) is 1.25 V, which is especially large for a semiconductor with a band gap of 1.55 eV. A PEC photovoltaic cell, with a configuration of p-MeNH3PbI3/CH2Cl2, BQ (2 mM), BQ(•-) (2 mM)/carbon, shows an open-circuit photovoltage of 1.05 V and a short-circuit current density of 7.8 mA/cm(2) under 100 mW/cm(2) irradiation. The overall optical-to-electrical energy conversion efficiency is 6.1%. The PEC solar cell shows good stability for 5 h under irradiation.

Optimization of Lead-free Organic–inorganic Tin(II) Halide Perovskite Semiconductors by Scanning Electrochemical Microscopy

“…The impressive properties of perovskite materials, e.g., MAPbX 3 (Me=CH 3 ; X= I, Br, or Cl) for photovoltaic (PV) devices include very strong light absorption, excellent ambipolar charge mobility, small exciton binding energy, and apparent tolerance to defects. [1][2][3][4][5][6] The remarkably high power conversion efficiency (PCE) of 22.1% reported for hybrid Pbbased perovskite solar cells was achieved by optimizing both series resistance and band positions. [7] However, the most extensively explored hybrid perovskite materials contain the toxic metal lead, raising concerns about their environmental impacts.…”

Characterization of optically active perovskite electrodes

“…Recently, it was demonstrated that (photo)electrochemical measurements can be performed in dichloromethane-based electrolytes in the presence of different reversible redox couples (e.g., ferrocene and benzoquinone). [152] The assembled liquid junction cells showed remarkable stability for prolonged irradiation. In this notion, electrochemical impedance analysis was performed to estimate the flatband potential and charge carrier density of different HOIPs.…”

“…In this notion, electrochemical impedance analysis was performed to estimate the flatband potential and charge carrier density of different HOIPs. [152,153] A very thorough study investigated the electron injection process into formamidinium lead halide perovskite using spectroelectrochemistry. [154] It was demonstrated in this study that it is very difficult, yet possible, to probe band edge positions via charge carrier injection.…”

“…Further complications arise from the dynamic exchange between the ions in the perovskite layer and ions present in the solution, which can alter the composition of the perovskite layer. [199] It has been demonstrated recently that the electrochemical properties of MAPbI3 [152,156] and related materials [153][154][155]157] can be studied in dichloromethane based electrolytes. However, special care must be exercised, because the use of an external electrochemical bias can also induce unintended side reactions (e.g., corrosion of the perovskite layer).…”

“…Given the sensitivity of perovskite films to polar solvents, one needs to exercise caution while drawing conclusions from the studies performed in aqueous media. [168,170] It should also be noted that conclusions obtained with certain special electrolytes, such as Li + or reversible redox couples [209] which are pertinent to certain specific applications, cannot be simply generalized. The researchers should provide data to support the stability test by monitoring the absorption and/or surface spectroscopy measurements before and after electrochemical measurements.…”