Dual-Doping Improves Heterojunction and Homojunction Photo-Charge Utilization Toward Transmission Spectrum-Tailored Organic Agrivoltaic Cells

Organic solar cells (OSCs) are promising for agrivoltaic applications due to their easily tailored transmission spectra to align with plant's photosynthetic profiles. However, they suffer from severe power conversion efficiency (PCE) loss caused by the donor-reduced morphology during spectra modulation. We propose to overcome this drawback by dual-doping in the active layer. To avoid ineffective doping arising from misallocated dopants, we employ the p- and n-dopants (TrTPFB and P2-t-Bu) with selective affinity for the donor and acceptor, and realize dual-doping via a two-step subsequential doping procedure. Benefiting from the simultaneously doping optimization of the binary component, the PCE of D18:L8-BO (0.08:1) significantly increases from 6.5% to 10.1%, which outperforms the singly p-doped and n-doped counterparts. Mechanism studies reveal that the dual-doping enhances photo-charge utilization at both the donor/acceptor heterojunction and the acceptor/acceptor homojunction. To comprehensively evaluate the merits of donor-reduced OSCs in agrivoltaic applications, we define the total light utilization efficiency (LUE_total) as a new metric that incorporates both photo-electric and photo-biomass conversion efficiencies. A champion LUE_total of 10.1% is achieved in the over donor-reduced condition, which even surpasses those of 7.3% and 9.2% under optimal bulk heterojunction (BHJ) condition and the conventional donor-reduced semitransparent OSC (ST-OSC) condition.