How Does the “Pecking Order” of Financing Channels Drive Green Innovation Efficiency? The Agency Cost Mechanism of Heterogeneous Financing Preferences in New Energy Enterprises under Dual Carbon Goals

H₆: Economic policy uncertainty weakens internal financing's role in GIE. Data & Variables Sample: 137 A-share new energy listed firms (2010-2023), filtered by *CSI New Energy Industry Index*, excluding delisted/ST firms with missing data. Data sources: Financial/governance data: CSMAR; Green innovation output: State Intellectual Property Office; City-level data: Municipal government work reports.

Key variables: GIE: ln(green patent applications+1)/ln(R&D expenditure+1)×100 (patents include inventions, utility models, designs). Internal financing (Interfina): (Surplus reserve + Undistributed profit)/Total assets. External financing (Exterfina): ln(Share capital + Capital reserve + Loans + Bonds payable).

Equity financing (Equity): ln(Capital reserve + Share capital). Debt financing (Debt): (Loans + Bonds payable)/Total assets. Controls: Largest shareholder ratio, fixed asset ratio, etc.

Key Findings Benchmark regression: Internal/external financing both significantly boost GIE (1% level), with internal financing more impactful (supporting H₁); equity financing matters (1% level), debt financing does not (supporting H₂). Robustness: Confirmed via variable replacement, cluster regression, and fixed effects adjustments. Mechanisms: Internal/equity financing reduce agency costs (supporting H₃); internal controls weaken internal financing (H₄); public attention strengthens it (H₅); policy uncertainty weakens it (H₆).

Heterogeneity: Effects differ by ownership (stronger in non-state firms), life cycle (internal financing matters in mature/declining stages; equity in growth/mature), competition (internal financing works in low-competition industries), and financing constraints (internal/equity financing matter more under high constraints). Innovation types: Internal financing promotes both substantive (inventions) and strategic (utility models) innovation; equity financing favors only substantive innovation.

Interpretation New energy firms’ GIE relies on "internal financing first, equity supplement," aligning with the pecking order theory. Agency cost reduction is key, with internal controls, public attention, and policy uncertainty regulating internal financing flexibility. Policies should differ by firm type (e.g., strengthening equity for non-state firms) to support "Double Carbon" goals.