Toward Long‐Term Stable and Efficient Large‐Area Organic Solar Cells

Abstract

Here, we report that long-term stable and efficient organic solar cells (OSCs) can be obtained through the following strategies: i) combination of rapid-drying blade-coating deposition with an appropriate thermal annealing treatment to obtain an optimized morphology of the active layer; ii) insertion of interfacial layers to optimize the interfacial properties. The resulting devices based on poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene-2-carboxylate-2,6-diyl)] (PBDTTT-EFT):[6,6]-phenyl C butyric acid methyl ester (PC BM) blend as the active layer exhibits a power conversion efficiency (PCE) up to 9.57 %, which represents the highest efficiency ever reported for blade-coated OSCs. Importantly, the conventional structure devices based on poly(3-hexylthiophene) (P3HT):phenyl-C -butyric acid methyl ester (PCBM) blend can retain approximately 65 % of their initial PCE for almost 2 years under operating conditions, which is the best result ever reported for long-term stable OSCs under operational conditions. More encouragingly, long-term stable large-area OSCs (active area=216 cm ) based on P3HT:PCBM blend are also demonstrated. Our findings represent an important step toward the development of large-area OSCs with high performance and long-term stability.

Highly efficient and stable organic solar cell modules processed by blade coating with 5.6% module efficiency and active area of 216 cm2

“…Here comes the advantage of PBDTTT‐EFT again. Among many other low band‐gap polymers, the efficiency drop of PBDTTT‐EFT by thermal annealing is the least for small‐area devices presumably due to the higher stability when blended with PC 71 BM. In large area, the cost of local reduction of efficiency in the micrometer scale can possibly be compensated by the overall improvement of the morphological uniformity through the tens of centimeter scale.…”

Thermally Stable High‐Performance Polymer Solar Cells Enabled by Interfacial Engineering

“…At 80 8C, the stabilityo ft he device with MSAPBS or PEI CIL is dramatically improved. [5] Results and Discussion Normal device structure [15] This result shows that, contrary to the conventional concept, the normal device structure also has the potential for real application.…”

“…[1,2] Althoughs ignificant enhancemento ft he powerc onversion efficiency (PCE) of such devices has been achieved, the improvement of device stabilitya nd the development of scalable depositiont echniquesr emainh ighly challenging. [5] The stability of polymer solar cells can be improved in variousw ays; [3,4,[6][7][8][9] for example,i nterlayer [10] and rapid-drying blade coating are known to be effective. Whereas, with sufficiente ncapsulation, the water and oxygen in air can, in principle, be well excluded, thermals tability is an intrinsic problem for many organic devices.…”

“…[3,4] The two major causes of degradation of polymer solar cells are air exposure andh eating. [5,11,12] Many studies have only trackedt he decay of efficiency for af ew hundred hours. High thermal stabilityo ver al ong periodi sacrucial criterion fora ny real applicationu nder sunlight.…”

“…After aging at high temperature ( Figure 4, right side), the film with the coated interlayer is relativelys table. [5] The high roughness suggested ah igher level of aggregation,e ven before the thermal stress.T he initial aggregation may lead to phase separation during long-term thermals tress. The PSC lifetimei sknown to have ac lose relationship to the activel ayer and metal electrode.…”