New polymer brings organic solar cells near 20 percent efficiency at one-fifth the cost

Researchers at Zhengzhou University have unveiled a low-cost polymer, PTQ15, that drives organic solar cells (OSCs) to a certified 19.96 percent power-conversion efficiency—an unprecedented figure for inexpensive organic materials. This advance positions OSCs closer to commercial viability while maintaining the lightweight and flexible qualities that make the technology attractive.

Producing PTQ15 costs roughly $35,528 per kilogram, about one-fifth of the price of established “star” polymers PM6 and D18, which exceed $200,000 per kilogram. Such savings stem from a streamlined three- to four-step synthesis that delivers yields above 80 percent, sharply lowering material and manufacturing expenses.

OSCs fabricated with PTQ15 and acceptors K1/K6 set the new benchmark efficiency of 19.96 percent. Measurements show ultrafast charge transfer in just 1.40 picoseconds and a minimal non-radiative energy loss of 0.190 electron volts—figures that reflect efficient exciton dissociation and reduced thermal losses.

Devices processed in open-air conditions at 25 percent relative humidity still achieved 19.37 percent efficiency. The study estimates a minimum sustainable cost of $0.36 per watt, placing these OSCs within striking distance of conventional silicon photovoltaics on a price-per-performance basis.

The next steps focus on surpassing the 20 percent efficiency threshold by refining donor-acceptor pairings and film morphology. If successful, PTQ15 could shift OSCs from laboratory prototypes to mainstream energy solutions, delivering economical, lightweight, and flexible solar power to a broader range of applications.