electrically benign

low-cost

near-single-crystalline semiconductors is crucial for large-scale applications

understanding the electrical behavior of small-angle grain-boundaries (GBs)

consisting of array of dislocations

becomes important. However

a quantitative microscopic theory is still prohibitively difficult. Here

by developing a multiscale approach combining Monte-Carlo simulation

elasticity theory

first-principles calculation

and grand-canonical statistical modeling

we quantitatively explain the recent experimental observation showing the disappearance of hole transport barrier in poly-Si when the GB angle approaches a critical value of a few degrees. It reveals the microscopic origin for the observation as a transition from electrically harmful dislocations to electrically benign dislocations.