Abstract
Herein we propose a new equivalent circuit including double heterojunctions in series to simulate the current–voltage characteristic of P–I–N planar structure perovskite solar cells. This new method can theoretically solve the dilemma of the parameter diode ideal factor being larger than 2 from an ideal single heterojunction equivalent circuit, which usually is in the range from 1 to 2. The diode ideal factor reflects PN junction quality, which influences the recombination at electron transport layer/perovskite and perovskite/hole transport layer interface. Based on the double PN junction equivalent circuit, we can also simulate the dark current–voltage curve for analyzing recombination current (Shockley–Read–Hall recombination) and diffusion current (including direct recombination), and thus carrier recombination and transportation characteristics. This new model offers an efficacious and simple method to investigate interfaces condition, film quality of perovskite absorbing layer and performance of transport layer, helping us further improve the device efficiency and analyze the working mechanism.
Highlights
The photoelectric effect converts solar energy into electricity, which is one of the promising ways to solve the global energy crisis and environmental pollution
In order to elucidate the effect of m on planar perovskite solar cell (PSC), we fabricated CH3NH3PbI3-based planar PSC devices with structure of ITO/TiO2/CH3NH3PbI3-xClx/Spiro-OMeTAD/ Au using two-step deposition method [23], in which methylammonium chloride (MACl) was added to increase the perovskite films quality
The addition of Cl- in the perovskite film significantly improved the efficiency of planar PSCs
Summary
The photoelectric effect converts solar energy into electricity, which is one of the promising ways to solve the global energy crisis and environmental pollution. By fitting J–V curves under light and in dark, three parameters including series resistance (Rs), diode ideal factor (m) and reverse saturation current (J0) can be obtained. For a single heterojunction model, the ideal factor approaches to 1 when the carrier diffusion in the neutral region of semiconductors dominates the diode current through a PN junction. The smaller value of m reflects the less carrier recombination induced by the interface defect state In most cases, both diffusion and composite currents exist simultaneously, and the parameter m is in the range of 1–2. Based on the new double heterojunction circuit, we found that smaller value of m reflects better PN junction quality in PSCs. carrier recombination and transportation characteristics can be further explored by fitting J–V curve in dark with the new model for describing these important processes in efficient PSC devices
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