Efficient heterojunction constructed from wide-bandgap and narrow-bandgap small molecules enables dual-band absorption transparent photovoltaics†
The main challenge in transparent photovoltaics (TPV) is to balance the competition between light absorption for photocurrent and light transmittance for device transparency. Herein, we used a dual-band light absorption strategy to enhance the photocurrent of TPVs while maintaining the high transparency. TPD-2TPA with a 2.48 eV bandgap and Y6 exhibit efficient selective absorption in the ultraviolet and near-infrared regions, respectively, which is ideally complementary to the human eye photopic response spectrum. The opaque device based on efficient TPD-2TPA:Y6 bulk-heterojunction exhibits a power conversion efficiency (PCE) of up to 7.34% with a short-circuit current density (JSC) of 18.7 mA cm−2. The TPV device with an AVT of over 70% can achieve a champion PCE of 3.31% without optical modulation. The dual-band absorption TPV device shows a photocurrent of 8.03 mA cm−2, which is superior to that of the NIR-absorption device. The flexible TPV device constructed at room temperature also further verifies its potential application in the field of flexible optoelectronics.