Sub-technology market share strongly affects critical material constraints in power system transitions.

Critical material constraints may limit and guide power system transitions towards net zero. Pathways to mitigate these constraints need to be evaluated and pursued to ensure successful transition. Here, we explore the material constraint mitigation pathways from the perspective of adjusting power generation sub-technology market shares, analysing nineteen critical materials that may cause material constraints. We find that the power generation system transition within China's carbon neutrality scenario results in 52.2 megatonnes of cumulative material demand by 2060, approximately 2.7 times that of the business-as-usual scenario. Solar photovoltaic and wind power sub-technology market shares have the greatest impact on critical material demand. As progressive thin-film solar photovoltaic sub-technologies gain market share, the demand for gallium from solar photovoltaic may increase 56-fold. Material constraints are likely to occur for gallium, terbium, germanium, tellurium, indium, uranium and copper. The importance value is determined by the ratio of power sector to all-sector material demand; the importance value of gallium will increase to 50% due to increases in gallium arsenide and permanent magnet sub-technologies. Our study findings show that sub-technology market shares need to be considered when evaluating future material constraints. Our results provide insights for future research investigating mitigation pathways.