Reverse Bias Behavior of Halide Perovskite Solar Cells

Abstract

solar cells have a breakdown voltage (V BD ) at which current starts to flow in reverse bias. When current flows in reverse bias, the shaded cell dissipates power rather than producing it, and this can cause local heating, which damages the cell. [8] Silicon cells generally breakdown in reverse bias by avalanche breakdown; the carriers gain enough kinetic energy from the applied electric field to generate additional carriers through impact ionization. V BD s for silicon cells are typically >15 V. If the pn junction is highly doped, the depletion width can narrow enough to allow tunneling in reverse bias. With either mechanism, breakdown current can get localized by uneven doping, crystalline defects, trace processing contaminants, etch sites, or edge effects causing damaging hot spots. CIGS and CdTe exhibit V BD s < 10 V and a decrease in V BD under illumination. This has been attributed to tunneling through defects at the buffer layer/CIGS interface. [9] Partial shading has been shown to cause local current flow and the damage is exacerbated by the light dependence of the V BD , which causes even more of the current to selectively flow through the illuminated region. This can cause localized shunting those results primarily in a permanent decrease in fill factor. [10] Stability in reverse bias has not been explored for perovskite solar cells, but there have been studies of MAPbI 3 memristors, [11][12][13][14] which require biasing in both forward and reverse directions, and photodetectors, which function in reverse bias. [15] Some memristors operate via the formation of metallic filaments through the perovskite [11,12] and others seem to function based on mobile defects in the perovskite. [12,13] Photodiodes of the structure fluorine-doped tin oxide (FTO)/porous TiO 2 /MAPbI 3 / Spiro-OMeTAD/Au show current multiplication in reverse bias, which has been attributed to mobile ion accumulation. [15] Mobile ions have also been used to explain hysteresis in current-voltage measurements. [16,17] In most cells, preconditioning at lower voltages makes cells worse, which is why scans from J SC to V OC tend to give lower efficiencies. It has also been demonstrated that mobile ions can cause band bending that can turn a symmetric device with nonselective contacts into a diode that functions as a solar cell. [18] Mobile ions likely also play an important role in the behavior of perovskite solar cells in reverse bias.In this paper, we first present a phenomenological study of reverse bias breakdown in halide perovskite solar cells. We characterize cells that have been held at constant current in the dark as they would be in a series connected module if only one cell were completely shaded. We also provide constant voltage measurements. We show how the reverse breakdownThe future commercialization of halide perovskite solar cells relies on improving their stability. There are several studies focused on understanding degradation under operating conditions in light, but little is known about the stability of these solar cells u...

I2 vapor-induced degradation of formamidinium lead iodide based perovskite solar cells under heat–light soaking conditions

“…1 Although light-to-power conversion efficiencies have rapidly increased to a certified record of 24.2% 2 (B0.1 cm 2 , initial efficiency), perovskite solar cells still suffer from relatively poor operational stability compared to commercial photovoltaic technologies. 3,4 It is well documented that extrinsic parameters such as moisture, 5 oxygen, 6 light, 7 temperature, 8 electric fields, 9 reverse bias, 10 strain, 11 etc. strongly influence the stability of perovskite solar cells.…”

Machine Learning for Perovskites' Reap-Rest-Recovery Cycle

“…Heterogeneous illumination presents a serious issue, as shaded regions of a single solar cell experience reverse bias, in contrast to other areas in the device that are under illumination. 68,69 Concerning light treatments, the substantial variety of possible illumination conditions must be emulated at the laboratory scale first in order for the ML analysis to perform well in real-world situations.…”

Multi-component engineering to enable long-term operational stability of perovskite solar cells

“…As a result, the accumulated charges at the interfaces lead to the formation of radicals and the observation of hysteresis in IV curves. Moreover, the induced external ion diffusion into the transporting layers and metal contacts provoke the formation of carrier traps and detrimental reactions [22][23][24]. In particular, it is reported that a reverse bias voltage of merely −1 to −4 V can cause the breakdown of perovskite solar cells, while the breakdown value for silicon solar cells is around −15 V [24].…”

“…Moreover, the induced external ion diffusion into the transporting layers and metal contacts provoke the formation of carrier traps and detrimental reactions [22][23][24]. In particular, it is reported that a reverse bias voltage of merely −1 to −4 V can cause the breakdown of perovskite solar cells, while the breakdown value for silicon solar cells is around −15 V [24]. The mechanism is considered to be the shunt path formation or the electrochemical reaction of defects in the contacts [24].…”

“…In particular, it is reported that a reverse bias voltage of merely −1 to −4 V can cause the breakdown of perovskite solar cells, while the breakdown value for silicon solar cells is around −15 V [24]. The mechanism is considered to be the shunt path formation or the electrochemical reaction of defects in the contacts [24].…”