Record indoor performance of organic photovoltaics with long-term stability enabled by self-assembled monolayer-based interface management

Though with the advent of the Internet-of-Things state-of-the-art organic photovoltaic (OPV) systems for harnessing indoor light energy have successfully been developed; however, the practical use of OPVs is limited owing to their low power conversion efficiency (PCE) and marginal understanding on the charge dynamics of OPVs under dim indoor lights. Herein, a record-high performance in indoor OPV system is secured by combining a 2-(9 H-carbazol-9-yl) phosphonic acid (2PACz)-processed indium tin oxide (ITO) and a 2PACz-mixed photoactive layer. Charge carrier dynamics of the 2PACz-mixed photoactive layer are systematically investigated to develop efficient indoor OPVs. Spontaneous vertical phase separation of photoreactive layers with 2PACz forms a vertical component distribution and dramatically improves carrier yield-mobility product which yields suppression of trap-assisted recombination and leaking current in the indoor OPVs. Also, phosphonic acid groups-based 2PACz-treated ITO leads to induce a sufficiently large work function owing to a vacuum-level shift, thereby enabling efficient energy-level matching to achieve charge selection enhancement at the hole-selective interface. The champion OPV (∼ 36% PCE under indoor lights) system maintains 95% of its initial efficiency after 1000 h of operation in ambient air. Our findings highlight the tremendous potential of indoor OPVs for simultaneously achieving high efficiency and ambient shelf-lifetime.