Our work suggests that there is a lower concentration than the overlap concentration, determined by the relative rates of singlechain collapse and multi-chain aggregation, which might more accurately predict the transition to extended aggregates correlated with good device performance. It should be noted, however, that the theory presented for the scaling of this critical concentration (ESI Section S9) breaks down at the overlap concentration as aggregation will be instantaneous (τ c = 0) when the chains on average overlap, resulting in a critical concentration that is ill-defined.