Isolating p- and n-Doped Fingers With Intrinsic Poly-Si in Passivated Interdigitated Back Contact Silicon Solar Cells

Revealing the Mechanism behind the Catastrophic Failure of n‐i‐p Type Perovskite Solar Cells under Operating Conditions and How to Suppress It

“…The potential‐induced degradation in photovoltaic modules could potentially cause the catastrophic failures of silicon solar cells and modules, making it difficult to predict the overall lifetime. [ 35,36 ] Although in most literature reports, the PSCs typically depicted an exponential decay process, we show in this paper that n‐i‐p type PSCs also undergo unpredicted catastrophic failures within tens to a hundred hours under light illumination. By systematical investigation on the aged cell, we prove that the undesired shunting of the cell mainly occurs at the edge of the Ag electrode, which is originally from the corrosion of Ag electrode by the photon generated reactive iodinated species.…”

Trap-Assisted Dopant Compensation Prevents Shunting in Poly-Si Passivating Interdigitated Back Contact Silicon Solar Cells

“…After the growth of the oxide, a blanket intrinsic a-Si:H layer was deposited. To form n- and p-type-doped fingers, additional P- or B- heavily doped a-Si:H films were deposited onto the intrinsic a-Si:H through in-house fabricated c-Si shadow masks as described previously in ref . This method can achieve alignment precision ∼10 μm for the 30 × 50 mm 2 samples used in this study, but may be more difficult at the wafer scale.…”

“…While previous studies using simulations have investigated the optimal dimensions, electrical properties, and passivation quality of the doped fingers, − a majority of these studies regard the region between the intentionally doped fingers as insulating. However, in experimentally fabricated devices, dopants are known to spread into the nominally intrinsic poly-Si isolation region between the n- and p-doped fingers through multiple mechanisms: diffusion during high-temperature annealing steps, incomplete masking, and gas-phase transfer . To mitigate dopant spreading in the isolation region, complicated processing steps would have to be incorporated.…”

“…According to Green, the cell fill factor FF is reduced due to R shunt according to the equation where FF 0 is the fill factor if no resistive losses existed, R shunt is the total shunt resistance of the cell, and R CH is the characteristic cell resistance defined as V oc / I sc . To prevent fill factor loss from shunting to below 1% absolute, the shunt resistance of this isolation region must be ∼1.5 kΩ·cm 2 or higher for a cell with an open-circuit voltage ( V oc ) of 700 mV and a J sc of 40 mA/cm 2 . , One method to isolate the n- and p-type doped regions in an IBC device is to create an engineered gap between the two types of doped fingers. However, this requires selective etching of the region between the doped fingers and repassivation of the underlying c-Si wafer in the gap to prevent loss in V oc , adding to process complexity and production costs.…”

“…We explore the dopant contamination of the intrinsic poly-Si isolation region from dopant tails originating from the adjacent oppositely dopped fingers (Figure b). We consider two types of dopant profiles: error-function-shaped dopant profiles created by lateral diffusion of dopants, or exponential-shaped profiles formed during masked plasma-enhanced chemical vapor deposition (PECVD) . While the primary focus of this work is of poly-Si p–i–n structures across doped IBC fingers, this type of structure has been demonstrated for use in other semiconductor devices such as electro-optical devices and coplanar thin film diodes. − We consider the effect of compensation in this region leading to reduced conductivity due to reduced net free carrier concentration, n eff .…”