Analysis of the Oxygen Passivation Effects on MAPbI₃and MAPbBr₃in Fresh and Aged Solar Cells by the Transient Photovoltage Technique

Abstract

Previous studies have revealed that for some perovskite compositions, power conversion efficiencies (PCEs) improved after storing the devices in different ambient conditions. With the aim of better understanding such improvements, we focus our attention on the carrier/ionic dynamic kinetics of fresh and aged PSCs with different perovskite compositions (MAPbI3 and MAPbBr3) and using spiro‐OMeTAD as HTM. For that, we use transient photovoltage (TPV), a technique used to analyse the different recombination kinetics at equilibrium and at different illumination times. We observe that the aging treatment causes significant changes on the kinetics behaviour for bromide‐based devices, resulting in a positive influence on the cell performance (from 3.5 % to 6.1 % PCE, in reverse scan). However, the kinetics for those iodide‐based perovskite solar cells remains unchangeable (from 16.3 % to 15.0 % PCE, in reverse scan).

Discerning rise time constants to quantify charge carrier extraction in perovskite solar cells

“…In the PSC community, only the decay of the photovoltage or photocurrent is typically analysed by fitting an exponential to obtain the characteristic decay time constant. 1,2,4,28 However, in the case of dye-sensitized solar cells, the characteristic rise time constants of the photovoltage were analysed and attributed to electron transport across the TiO 2 layer 5 while for organic solar cells, the rise of the photocurrent was analysed to get insight into charge trapping. 29,30…”

“…6) for an intrinsic perovskite layer and undoped transport layers, while t rec is a function of the internal voltage (quasi-Fermi level splitting) (eqn ( 6)), that can also vary as a function of the light intensity and V elec . 47 Therefore, the FOM is also a function of V elec (eqn (28)) and can be used to calculate losses related to non-ideal charge extraction at each bias point of the current-voltage curve. The FOM is particularly useful to determine losses at short-circuit and low forward bias that can strongly affect the fill factor in state-of-the-art PSCs.…”

Discerning Rise Time Constants to Quantify Charge Carrier Extraction in Perovskite Solar Cells

“…In the PSC community, only the decay of the photovoltage or photocurrent is typically analysed by fitting an exponential to obtain the characteristic decay time constant. 1,2,4,23 However, in the case of dye-sensitized solar cells, the characteristic rise time constants of the photovoltage were analysed and attributed to electron transport across the TiO2 layer 5 while for organic solar cells, the rise of the photocurrent was analysed to get insight into charge trapping. 24,25 In the simplest scenario, we can assume that both the rise and decay occur exponentially, where the rise of the quantity is proportional to 1 − exp (−𝑡𝑡 𝜏𝜏 rise ⁄ ), while the decay is proportional to exp (−𝑡𝑡 𝜏𝜏 decay ⁄ ).…”

Methylammonium Tetrel Halide Perovskite Ion Pairs and Their Dimers: The Interplay between the Hydrogen-, Pnictogen- and Tetrel-Bonding Interactions

“…All-inorganic perovskites that have impressive optoelectronic properties include CsTtX 3 [ 54 , 55 ] and RbTtX 3 [ 56 , 57 , 58 ]. MAPbI 3 and MAPbBr 3 [ 59 , 60 , 61 ] have been applied in third-generation photovoltaics (efficient for photo-energy conversion).…”