Light Soaking Effects in Perovskite Solar Cells: Mechanism, Impacts, and Elimination

Abstract

Perovskites solar cells (PSCs) have been recognized as one of the most prospective photovoltaic technologies for their combined properties of simple fabrication process, low material cost, and remarkable power conversion efficiencies of over 25%. However, the instability and poor reliability of PSCs remain the major obstacles to their practical applications. Specifically, light-soaking effect (LSE), which refers to the fluctuations of photovoltaic parameters under light exposure, represents a critical factor limiting the accuracy and stability of device power output. However, great challenges still remain in understanding and modulating the LSE in PSCs. In this review, we discuss different transient behaviors associated with LSE, and summarize various physical mechanisms (such as light-induced ions migration, trap defect passivation, lattice expansion, and charge carrier accumulation) behind the LSE together with their impacts to the device performance. Moreover, we systematically review the recent advances in developing effective approaches and strategies to mitigate or eliminate the LSE in PSCs, including interfacial modification, material doping, and surface passivation. Finally, a perspective and outlook toward LSE-free PSCs are further provided. This review offers a deeper opinion of the LSE physics with further guidance on ways to optimize the photostability of PSCs.

Oxygen-Mediated (0D) Cs4PbX6 Formation during Open-Air Thermal Processing Improves Inorganic Perovskite Solar Cell Performance

“…The accelerated stabilization of photocurrent in the open-air device is attributed to suppressed activation of light-driven dynamics, like ion migration. 49 Both devices exhibited good stability under light soaking conditions (Figure S25). Together, these observations confirm the passivating effect of oxygen-mediated 0D perovskite formation.…”

Regulating Surface Defects to Achieve More Positive Light Soaking Effect in Perovskite Solar Cells

“…Under light illumination, MHPs exhibit various anomalous phenomena, including fluorescence enhancement, , defect curing, , fluorescence blinking, and phase segregation, which can intimately correlate with the performance and stability of perovskite solar cells . This represents a critical factor limiting the accuracy and stability of the solar cell device’s power output . The underlying physics of LSE is highly complicated and can exhibit either beneficial or detrimental effects.…”

“…The severity of the light soaking effect is reported to vary from laboratory to laboratory and remains the subject of intense debate regarding the underlying mechanism . One of the proposed scenarios is the trap-filling/detrapping mechanism, , in which traps are filled under illumination.…”

Photoluminescence Mapping over Laser Pulse Fluence and Repetition Rate as a Fingerprint of Charge and Defect Dynamics in Perovskites

“…[4][5][6][7][8][9] Despite extensive studies, many contradicting observations have been reported that continue to puzzle researchers. The main challenges of working with perovskites are: i) poor sample storage stability, ii) poor reproducibility in sample fabrication, [10,11] and iii) evolution of the material under light irradiation, current flow, and electric field [12][13][14][15][16][17][18] and material self-healing. [19][20][21][22] Most of these difficulties, as well as advantages like, e.g., self-healing originate from low energy of defect formation, easiness of material recrystallization, [5] the ionic nature of the defect states and their metastability [22][23][24][25][26] due to very efficient ion migration in MHPs.…”