On the Uniqueness of Ideality Factor and Voltage Exponent of Perovskite-Based Solar Cells

Abstract

Perovskite-based solar cells have attracted much recent research interest with efficiency approaching 20%. While various combinations of material parameters and processing conditions are attempted for improved performance, there is still a lack of understanding in terms of the basic device physics and functional parameters that control the efficiency. Here we show that perovskite-based solar cells have two universal features: an ideality factor close to two and a space-charge-limited current regime. Through detailed numerical modeling, we identify the mechanisms that lead to these universal features. Our model predictions are supported by experimental results on solar cells fabricated at five different laboratories using different materials and processing conditions. Indeed, this work unravels the fundamental operation principle of perovskite-based solar cells, suggests ways to improve the eventual performance, and serves as a benchmark to which experimental results from various laboratories can be compared.

Band Gap Tuning of CH3NH3Pb(Br1–xClx)3 Hybrid Perovskite for Blue Electroluminescence

“…There are no reliable values for µ r and κ reported for the mixed chlorine-bromine perovskites. If we assume the effective mass to be that of the free electron mass, using Equation 6 κ is estimated to be about 16.5, which is close to recently measured for ABI 3-x Cl x (κ ≈ 18) case using capacitance measurement. 29 We now briefly comment on the broadening of the exciton peak.…”

Interfacial Kinetics of Efficient Perovskite Solar Cells

“…In this model, the dark current carrier recombination in the bulk and space charge region (SCR) is represented by a diode equation Hall (SRH) as a dominant recombination mechanism. In some cases, the ideality factor m is greater than 2, and this behavior is ascribed to the nonlinear shunt resistances across the junctions and/or a significant voltage drop across ETL and HTL [28]. The voltage drop across a diode has the form of Considering the fact that the accumulation mechanism is due to the electronic and ionic contributions, the accumulation resistance R acc may contain the information about the recombination and ionic components.…”

“…Crystals 2017, 7, 252 3 of 9 cases, the ideality factor m is greater than 2, and this behavior is ascribed to the nonlinear shunt resistances across the junctions and/or a significant voltage drop across ETL and HTL [28]. Considering the fact that the accumulation mechanism is due to the electronic and ionic contributions, the accumulation resistance may contain the information about the recombination and ionic components.…”

Sensitive, Fast, and Stable Perovskite Photodetectors Exploiting Interface Engineering

“…17 From this, the reverse saturation current density of the diode, J 0 , is estimated to be on the order of 10 pA cm -2 from V oc = nkTq -1 ln(J sc /J 0 + 1), where k is Boltzmann's constant, T the temperature, and q the electronic charge. In reality, the total dark current density, J dark , includes both the aforesaid contribution from J 0 , and also any parallel shunt path currents.…”