Ambient layer-by-layer ZnO assembly for highly efficient polymer bulk heterojunction solar cells

Ambient layer-by-layer ZnO assembly for highly efficient polymer bulk heterojunction solar cells

Ambient layer-by-layer ZnO assembly for highly efficient polymer bulk heterojunction solar cells
Mohamed Eita, Abdulrahman El Labban, Federico Cruciani, Anwar Usman, Pierre M. Beaujuge and Omar F. Mohammed
Advanced Functional Materials, 25(10), pp 1558–1564, (2015)
Mohamed Eita, Abdulrahman El Labban, Federico Cruciani, Anwar Usman, Pierre M. Beaujuge and Omar F. Mohammed
Layer-by-layer ZnO nanoparticles, Polymer donor PBDTTPD, Fullerene acceptor PCBM, Bulk heterojunction
2015
The use of metal oxide interlayers in polymer solar cells has great potential because metal oxides are abundant, thermally stable, and can be used in flexible devices. Here, we report on a layer-by-layer (LbL) protocol as a facile, room-temperature, solution-processed method to prepare electron transport layers from commercial ZnO nanoparticles and polyacrylic acid (PAA) with a controlled and tunable porous structure, which provides large interfacial contacts with the active layer. Applying our LbL approach to bulk heterojunction polymer solar cells with an optimized ZnO layer thickness of ca. 25 nm yields solar cell power-conversion efficiencies (PCEs) of ca. 6%, exceeding the efficiency of amorphous ZnO interlayers formed by conventional sputtering methods. Interestingly, annealing the ZnO/PAA interlayers in nitrogen and air environments in the range of 100-300 oC reduces the device PCEs by almost 20 to 50%, indicating the importance of conformational changes inherent to the PAA polymer in the LbL-deposited films to solar cell performance. Our protocol suggests a new fabrication method for solution-processed polymer solar cell devices that does not require post-processing thermal annealing treatments and that is applicable to flexible devices printed on plastic substrates.



DOI: 10.1002/adfm.201402637